It wouldnt be a breeding ground for bacteria, its running which makes the bacteria less likely to be able to survive in it (not incapable, just less likely). It would, however, bump your humidity up like nobodies business, I wouldn't suggest high humidity substrate with it. Your snake may not drink from it, you might want a small bowl near it so it can drink. And watch your humidity levels, too much can cause scale rot.

The vibrations will actually travel through the tank, but it will be constant so it wont be as irritating as a bass speaker or an unstable fan. Psychologically your snake should be fine, but know that BPs have a tendency to find ways to knock things over, if it's hard and it's in a glass tank it could smash right through if it falls over.