"How reliable is it?" should be at least as good as any other Springfield (which is pretty danged good, SA seems to have concentrated on 1911 reliability over accuracy)
"Will it take other 1911 parts?" a very few. pretty much sights and grips, IIRC.
"Can I get magazines w/o the "slam pad"?" probably. personally, I like slam pads.
"What is it's ammo capacity? " I think 7+1 in 9 and 6+1 in .40