For the quad-boob issue, is there a way you can put the top strap-to-bridge edge on a fold? I don't know what kind of seam arrangement your bra has (this would be easiest on a bra with a slanting seam running roughly parallel to that edge), but a folded edge is going to have more give to it than a bound and stitched edge. If that doesn't do it, you could put it on a bias fold, or use a stretch material.
For the support, it seems like using a firmer fabric (or stitching/cording what you've got) and/or some light bones would probably help. I suspect you may need both, because bones won't do you any good if the fabric isn't firm enough to hold them up - much like with corsetry, it's your fabric which must to the work, and any boning is just there to keep it from wrinkling or sagging in on itself. Try stitching two or three layers of your firmest bra fabric together (maybe with some of that foam Mark sometimes uses as a middle layer) and see if that makes a difference in the support.
The materials issue probably just means buying new, I'm afraid. Hopefully you'll be able to pass on the rest to someone else who can get some use out of it.
If you have any pictures/sketches of the current construction, they would be really helpful. Doesn't have to be on you.
