1 yes
2 yes
3 yes
4 yes, better in rear case first, unless you have an ultimate with 4.70s in the rear, then you can use stock gears in the front case with the rear in 4H.
5 high on the road, neutral won't get you far
Use the rear filler plug to fill.
Depending on how much lift you have you can use the crawl box for the cross member, but if you have a lot of lift you will have to move the cross to the rear case so the drive shaft doesn't interfere with the cross member.
By the way congrats on the crawler, you're gonna love it.