I remember you from the Cleghorn run. I started with the exact same Jeep as you, even same color.
I agree with all of the above and have already had some work done by Stan at JPI (about to do my new axle too). What I had installed by him was an Evo 3 piece skid set and front and rear PSC diff covers. I highly recommend the skid set I got which is custom designed for the 2012 JKU.
EVO: Bumper/Armor/Skids, EVO MFG(5) ProTeK Skid System for 2012 Jeep JK Wranglers
Regarding the evap skid, you already have one of those on the 2012, so not needed. However, I recommend moving it to the left a bit or even relocating the evap. I was in Calico about a month ago and the rear driveshaft boot got torn on the evap skid.
If you want 35's and a lift, you will want to do the lift first and/or do the tires at the same time.
I also went with Rock Krawler, went with the 2.5" max travel. It will fit up to 35's, or 37's with flat fenders. 3.5" would also be great with 35's. As mentioned, if you go that high, you will need to replace the front driveshaft, won't need to replace the rear.
Regarding the front axle, I agree that sleeve and gusset is a good idea. I was actually looking at doing the same, and then decided I wanted a locker in front too. I was looking at the cost of the locker installed + sleeve + gusset. To make a long story short, I have a Rubicon D44 complete axle on it's way, got a really good deal on it, slightly used. Probably not a practical decision for most though.