Realistically should a quarter panel fit pretty close without any clamps or is it normal to have to twist it a bit and hold it in place before welding?
It shouldn't have excessive pressure when it's on there. If so maybe some of the inner structure is bent or damaged. I used self taping screws with 5/16 head and the smallest vise grips, I think 4 or 6 inchers. Good luck
don't expect to much get the panel fitting as good as you can , then cut, slice to get it fitting , I wish I new now what I new 5mouths ago I wasted a lot of time going back and fourth ,