S.J.
Hi O.,
I think the night terrors are pretty common for his age. You might try adjusting the amount of light in his room at night. Also, when he wakes up, reassure him that everything is OK. Talk to him about what he's scared of and try to reassure him before he goes to sleep. You might also get some "monster spray" (Glade makes some nice varieties) and have him help you spray his room before he goes to bed. I gave my son a squirt bottle with a little water in it "for emergencies" and I sprayed a little Lysol, Oust, or Glade room freshener in there before bed for a few days and told them it was like bug spray for monsters. It helped a lot.
As for getting his legs stuck in the crib. Another option would be to take a big sheet (King or queen size), put it under the crib mattress and up over the sides of the crib bumper and pin it into place. That way, he can't get under it, but he can't get stuck between the rails either. I hope I explained that enough. My mom had to do it with my brother.
Good luck!