First hand - min-raise to me smells like a draw, probably straight. Big raise is definitely called for.

Second hand - I'd probably fold. He could have a higher flush or a house... that raise is just a little too hefty to call.

Third hand - call, I think. What was your read exactly? The ace couldn't have helped him; if he had you beat he had to have flopped the straight (or set). I could imagine him having AJ there, maybe.