that window regulator question is unclear - can't you cut the rivets from the other side? once you rip it apart, the teeth should move - best way to repair those things is replace the whole works
there ain't a "best way" to do something wrong! if you don't have a way to swedge the rivets, use short screws
for the hood spring, grab the loose end with a pair of vise grips and brace yerself - might need someone with more pull to get it
Bill