Yeah, but don't do that while wheeling with fellow Yotatechies, or you'll want too much too soon (or a whole new truck in my case)

Definitley get a locker. Selectable would be nice, but auto lockers are far cheaper and get the job done.

 

How about strengthing that front axle with a truss so you eliminate that as a potential problem with bigger tires/gears. If the power on road is good i would add t-case gears first, it's amazing what a much better crawl ratio can get you through.

As far as tires wait a bit IMO, wheel it and figure out what if any lift you are going to add so you can get the right size tires, gears to compensate etc. without having to do things twice.