1. there are a fair few yes, Nitro and Silver Star are two examples.
2. (I assume you mean on a log flume) the highest drop on a LOG flume I know of is the one in Phantasialand Germany, it's about 60ft, but the highest water chutes are the intamin vertical chutes e.g. Hydro (UK) and Perilous Plunge, I think they're about 100ft... Jurassic Park River Adventure is 85ft I think...
Hope this helps!