To touch on a few of your questions;
The standard, off the rail Raiders jacket from Wested is a great one, and apparently their best seller (according to the Wested site) so that's a good choice for a first Indy jacket I think.
Im not sure the Last Crusade is better, just different. Slightly bigger arm holes, ideal for the larger gentleman, and sloping shoulders give the jacket a looser, more slouchy feel in my opinion. It has a pointier collar than the Raiders and the adjustable straps are a little lower, and of course it has press studs on the storm flap. Ive found the Raiders has a more fitted look.
I think the distressed lamb is a beautiful looking skin, can be quite inconsistent in colour though. Ive seen some that are a rusty brown, but ive also seen some that look positively yellow-ish. The pre distressed hide tends to be a bit more consistent in colour, darkens nicely with a bit of the standard Pecards, responds well to the shower treatment, and ages really well.
The shower treatment. Fully zip up the jacket, hang it in the shower and wet it evenly all over, then simply wear it until it dries, preferably outside but not in direct sunlight. This causes the leather to quickly conform to the shape of the wearer and gives a well-worn look in just a couple of hours without any damage to the jacket. Ive done it many times to different jackets over the years, works great Ive found. (Check out some of my posts on this thread)
As an alternative, might be worth considering dark brown novapelle. Achieves a nice, worn-in look fairly quickly.
Hope this is helpful.