Vladimir can get out of Jarvan's ult with the pool, he just walked straight through it, it looked kinda glitchy, but managed to get out fast. This happened repeatedly throughout the game, so it's not a one time bug

Unfortunatly, its just the way his ult works. Ghost lets you run though his ult as well. Any ability/effect that lets you pass through units will let you out of his ult. I think Hecarium can NEVER get stuck in his ult, but i'm not sure on that

Oh god just think about anyone with a phantom dancer.