I'm just going to be devil's advocate here...
No offense to you, as we were all n00bs once, but you are asking a great deal of questions that modest experience would have answered for you already. I'm not being critical here, but again, why do you want to run 37's? I don't think there is anyone on this board who jumped from new XJ to XJ on 37's. Those that got there, did so out of necessity and slow buildups. I know you said you are going to do it slow, etc, etc, but what you are talking about running will really end up costing large in the end here, and judging by some of your questions, I am concerned that you are building up something that will overwhelm your skill, knowledge and expertise. If you have a whopping bank account and don't mind having others do the work, then by all means have at it, but remember that when you get work done, the majority of the cost is labour. You can save huge by doing it slowly, learning to drive your rig in progressively more advanced terrain and work it into exactly what you need, all the while learning to do it yourself. You have some major fabrication ahead of you, not to mention advanced design. A locked and armored XJ on 31's and 3" of lift will go many many places, lots of people on here have proven that over and again. Just a thought...