More answers than you can shake a stick at in past year's AZTR threads, but that can be a hassle to search back through to find the right forum threads.  Still worthwhile for the gems of info that are there, if you can tease apart what's still current from what's out-dated.  To spare you some hassle, here's my 2c:

1. Any suggestions for getting to the start of the 750? My plan is to fly to Tucson but don't know how to get to the start line from there.

a. Arrive a few days early and ride from Tucson (adventure points!);
b. Online search and book a ride from one of the handful of commercial shuttle services to/from Sierra Vista, then ride from there up and over Montezuma Pass;
c. Follow this forum as ColoRADo/Wyoming/Idaho peeps start organizing shuttles (will heat up in March), and hitch a ride with one of several groups - the 750 peeps driving down from the North sometimes drop a car at Stateline CG or the nearby TH, thereby having a ride out at the end waiting;
d. Follow this forum for word of locals that are just plain cool and awesome and offer rides (thank you Steve Osborne, circa 2014!);
e. One of the bikes shops (from Sierra Vista I think) has done a shuttle van the past few years - to Parker Cyn TH though, then you ride the 14m South to the border start (either night before or morning of); there were several riders last year that pedaled the P.Cyn TH to the border prologue.
f. Spearhead your own PNW shuttle group ... maybe I'm going for a 3rd 750 start in a row - I'm not sure yet, maybe Addy from Vancouver (CA) is going again?

These questions have been asked a few times, but I haven't seen answers.
2. Once finished and at the Utah border what is the best way to go. I'm looking to ride to civilization to rent a car. To where should I ride? What is the safest/quickest route?

a. Can't speak for safety, as that's variable, but based on my experience I'd ride North then West to Kanab, there's a dirt road cut off in there and the 89 has wide shoulder; shortest compared to East to Page or South to 89A, but may not be the quickest depending on your energy levels and which way the wind is blowing;  Kanab is SW touristy for sure due to proximity to Zion;  I wanted to fly out of LV, so I went Kanab->St George (hotel)->LV (airport shuttle from St G);  some peeps want to exit via Flagstaff, so they ride East to Page then go from there; at one point I thought I'd ride back to Jacob Lake, but it's all downhill from there to the finish so the closer I got to the finish the less appealing that option was and JLake doesn't have much (understatement);
b. In case you're tempted to hitch hike - still 'illegal' in Utah as far as I know, so riding south to the 89A in AZ is better option for hitching but less traveled of a road compared to the 89 in Utah, and slightly more remote;
c. Change your mind on riding out from the fin? - Find out who's gonna have a "drop car" at Stateline or the nearby TH for The Wave and get lucky, or pedal up to the TH from the fin and get lucky with catching a ride;

Is 13 hours really the fastest hike through the Grand Canyon during the AZT? That surprises me. I suppose all that extra bike and pack weight really would make a huge difference in the pace one could sustain. This would be a fun sub-statistic to keep in the overall record.

I'd be into comparing GC portage hikes as a sub-stat.  When I had more free time earlier this year I clicked through some historical dot data from past couple years.  Just looking at hike time, not disassemble/reassemble times, faster hike times are around 10hrs (a 2.5mph avg is a good clip).  There might even be a few 9.5hr times in the Trackleaders portfolio records.  Would take some hunting and pecking.  My watch said 10.5hrs in 2014,  but the spot data on TL records something closer to 11hrs (13 if you count 45mins to an hour at each rim to take bike apart, load it up, then put it back together).  It is hard to compare, though, because people arrive at different times of the day, in different weather, at different energy levels, etc..  Hiking at night might be slower, although there prob wouldn't be mule trains at night (a 10min 'delay' I experienced).  And, then there's Phantom Ranch ... I just had to stop and shell out $5 for a lemonade ... it was that perverse of a motivator (and reward) ... and probably burned 30min or more sitting there on a rock talking to other tourists.

does rain turn any portion into gumbo mud?

My first-hand experience with nature's own peanut butter, 2014 running of the 750, captured in this pic.  Locale: Russell Tank section.  Drying out in the sunrise after slogging it out in the wee hours of the night.

Go Aaron Johnson!  Looking good!  Well, at least your dot is moving fast.  And JayP's dot is pink because ... ?

I am still in deming nm
Can't seem to hitch a ride to hatch or las cruces
This may change quickly
But as of now I am looking for a ride to albq or Denver

Congrats on another great ride, Mark C!

Guess I turned my spot off to quickly or put my bike in the car before it pinged me but I finished at 18:8:09

Congrats on a great ride, Robert!

Alice! You are awesome! Užastný výkon.  Must've been the gas station danishes, again.  Now, rest up for a go at the CTR.

So awesome to watch fast women blaze the route like that.

And AliceD is flirting with finishing sub-20 on her SS.  Come on AD!

...  It's a trade secret but let me assure you Kathy's pie at Pie-o-neer Pies very well might have been the deciding factor in my race.

Cheers to you all!  Happy trails and best wishes to everyone on trail and congratulations to everyone who has finished.
Josh Kato

Kato the Cashmere Comet!  Well done.

Hard to believe that Lael would not be credited with the women's win and overall 6th place finish.

She gets full credit in my book, based on all details available that I'm aware of.  Outstanding and inspiring ride.

And Jefe last year was about 12 hrs. I think 9 hrs is completely realistic for this group. Also depends on the way the wind is blowing...

Right.  Temperature perhaps, as well.  Probably not fickle and random border patrol stops along the Lonely Highway during the day, through.  Got the photo finish camera set up yet, Lindsay?

In JayP's record run he did Silver City to the finish in 11 hours on the dot. It is worth mentioning that he was riding alone and already knew he had the record - I have a feeling these three will bust out Silver City to the finish in less time than the record shows, because there is such a high level of competitiveness right now. If they depart Silver City by 11am this morning, I wouldn't doubt they could finish between 8pm - 9pm tonight. Maybe even sooner as these three have already exceeded everyones, and I'm sure their own, expectations.

Some other comparatives: KurtR, circa 2011: ~9hrs Silver City to AW (through the night); MikeH, circa 2013: ~9hrs Silver City to AW (mostly daytime)

Ah, yes!  Friendly wager time.  Like years past with "can you guess the winner's finish time?" Cordillera give-away initiated by original TD Cordillera editor Eric Bruntjen.  JoeP of mtbcast ... what say you?  Mr. Bennett, a throwback Cordillera giveaway perhaps?  Ha, better yet: Salsa jumps into the forum and offers up a new Cutthroat frame for anyone that can guess the winner and the finish time within a 10minute window, before the current top 3 leave Silver City.  Or, even better yet, Cjell Mone offers a custom frame build to anyone that can guess Team Ricer Burner's finish time before a certain cut-off.  How's that for subtle hints? ...

You know, like this:
http://www.bikepacking.net/forum/ultra-racing/td%2711-race-discussion/msg21792/#msg21792

Anyone have an guess on what time these guys will finish?

Ah, yes!  Friendly wager time.  Like years past with "can you guess the winner's finish time?" Cordillera give-away initiated by original TD Cordillera editor Eric Bruntjen.  JoeP of mtbcast ... what say you?  Mr. Bennett, a throwback Cordillera giveaway perhaps?  Ha, better yet: Salsa jumps into the forum and offers up a new Cutthroat frame for anyone that can guess the winner and the finish time within a 10minute window, before the current top 3 leave Silver City.  Or, even better yet, Cjell Mone offers a custom frame build to anyone that can guess Team Ricer Burner's finish time before a certain cut-off.  How's that for subtle hints? ...

Edit: and perhaps something for correctly guessing how much time LaelW will break the record by?

Yes ElliotD!  Keep reeling in those blue dots!  MarshalB and RobertO ... and everyone else ... making it look easy to go sub-20!

Well, I dunno, JoshK just arrived in Cuba only 1hr to 1:15 behind JayP and NeilB.  1 hour ain't nothin', as they say.  Or, it's everything.  Anyone's ball game.  From what I saw first hand in AZ earlier this year, DylanT has a motor, too (if that isn't evident enough already).  Maybe AlexH has "thrown in the towel", but I'm not counting DylanT out just yet.  They're all going to fly across NM flats, then the run through the soft sand to Pie Town, and the Gila after that.  I haven't checked the weather forecast ... rain could still maybe factor? There's a ton of miles with clay dirt still to traverse.

Also, just linked with Nobo Jeff Taylor's FB page ... apparently he was hit by a wind/storm felled tree???  Just outside Kremmling.  Mild concussion.  Rested up in the 'boat, now headed back out on route to finish riding to Banff with new fork, bars, other parts?  What a story.  Nails.

AndresB from Uruguay looks to have missed the Gold Dust connector (yesterday).  Aagh!.  A few other riders look to have missed the turn to the GD trail, yet back-tracked to ride it.  RobD looks to have back-tracked this morning from Poncha Springs to Salida - bike repair or forgot something? - but all sorted out.  Race for 3rd among the pink dots is tight ... come on AliceD!

Neil and Jay slept on the porch of a building - not in beds. I thought that with the reroute this year the total mileage was down almost by 100 miles - I think they have just under 400 miles to go! Maybe I am wrong.

So no hotel/bed sleep so far the entire route?  Style points!  Looking at TL track, btwn Abiquiu and AW, there's ~570miles of track to pedal.

Spot dots show Jay and Neil at Bode's early, waiting for it to open, then Josh rolling up to Bodes before 7am.  Chances are they had a 'meeting'.  Fist bumps all around, I hope.  Spot dots show Neil and Jay leaving Abiquiu (~7:10am) 30mins before Josh (~7:40am).  Approximately 500miles to go.  Josh stopped early last night, so is on 6 to 6.5hrs rest, just about same about of rest for Neil/Jay.  Although hotel rest maybe better?

DylanT 45miles back as of 10:15am, with AlexH another 25miles back of DylanT.

And then there's LaelW ... she's just riding awesome, and just moved into 6th, by spinning past Sargents while the 3 boys she was catching up to yesterday stop for food/provisions.

And 17yo WillB now just outside the top10 in 11th, followed closely by the ageless RobertO (who took an entire zero day in Butte, remember?) in 13th, and don't count out ElliotD (yeah, buddy!) not much further back in 14th putting together a solid ride coming from way back in the pack and steadily making up ground each day.  Wow.  I'm in awe of this year's cast of riders.

At this rate, I wouldn't be surprised if Seb found a way to get a new fork in Chama, or sent there, and got back on course.

Stretching and foam roller. Like lubing your chain, just a little maintenance goes a long way!

This.