At that speed, he would skip out of a pool like a rock...
Doubtful...his entry angle is too steep. It also looks like the slide is already wet, probably from rain.
I'm skeptical because the water pool looks to be sitting on a wood platform. I'd expect the pool to move a little (if not break like kopjager said) when he lands. I'd also expect the guy to get injured...I don't think that small amount of water would do shit for cushioning, especially given the wood platform.