I'll reiterate the sentiments of all above posters in saying that search is your friend. You'll find a nice bit of information to supplement the responses you find here.
But I'll bite and help out.
It depends. You should be OK, and you may even be OK without sleeving your axle. It will depend on several factors, including tire weight/load range, wheel weight, and how you wheel. If you're a technical wheeler, you've got a better chance of being OK than if you're a rock bouncing throttle jockey.
I've run a set of 35s on a D30 front without sleeves or gussets for a while now, and have not had any problems other than my ball joints going bad (but the factory ones are junk IMO anyway). I tend to be more of a technical wheeler.
You will arguably get more value out of upgrading your shafts instead of sleeving your housing.
It depends. This is purely a preference issue.
Some guys like wheeling autos because they can focus on brake/throttle instead of brake/throttle/clutch/shifter. I personally like a manual transmission ... for many reasons. On the trails, I believe it gives me more control.
It depends. Ditto on what kkuntz01 said. If your rig will see a lot of highway time in 4wd (for whatever reason), you may unnecessarily tax your engine with the 4:1 transfer case on top your lower gearing (assuming you swap out your factory 3.21/3.73/4.10 gears for something in the 4.88/5.13 range). The Sport/Sahara transfer case will work just fine for a lot of wheeling applications.
Other things to consider:
Rubicons have electronic lockers, Sports/Saharas don't. Rubicons have a slightly beefier D44 front.
Do you plan to build it up at all in the future? Depending on how far you want to push your build (and in what direction), a Rubicon premium may not be worth it. For example... Do you prefer air lockers? Are you going to run 40"+ tires? Would you like get a higher crawl ratio than you can get with a 4:1 transfer case (e.g. with an Atlas or similar transfer case)?
Evaluate your use cases and preferences prior to next year's tax season, and that will help you decide between the Sport, Sahara, and Rubicon models.