i'm sorry i can't be of great help right now; i've got my own problems to deal with.
But i also know there is a disk brake kit available for the 73-87's. i can't remember exactly where i saw it, but will let you know when the info becomes available again. This saves about 12lbs over stock drums.
2) i think the B-bodies, certain ones, had alum drums. Again, i can't remember the exact details, but i'm sure the b-body sites can help. As you may know, many b-bodies also had the 5x5 bolt pattern.