I havent seen anything bad about Ballistic Advantage barrels. I brought one on Black Friday, a 8" 300blk so I was researching them then. Havent been able to fire through the barrel yet though, its a WIP
No. That one will slip between your frame and your grip. It's the easiest way to do it but also the least stable and likely the least preferred one to do it
Thats the Stormwerks hinge. I think you want this one
Actually I think this is the one you want. It's exactly like mine but for AR stocks
http://stormwerkz.com/stock-folding-mechanisms/stock-folding-mechanism-ar-type/
I've only did the Boys stock and DIP bottom. I'm not a trigger junkie so I just set my accu-trigger to a nice pull. I dont think I've heard anything negative about the Apachee though.
With regards to bedding the stock, its up to you, is it just a .22 and its unless you're going to be entering...
Definitely shoot it before touching the trigger.
This manual has been highly recommended if you want to learn about the 1911: http://www.brownells.com/gunsmith-tools-supplies/books-amp-videos/books/handgun-gunsmithing-books/us-m1911-and-m1911a-shop-manual-volume-ii-prod13815.aspx
Its an AR, dont worry too much about the headspacing. As long as you are using quality mil-spec bolt and barrel you should be fine. If you got some $50 junk then I would be worried about something being out of spec. This is a AR, not a precision bolt action.