1. Yeah I think vibration is a more general thing than oscillation, oscillation is mainly used in the context of waves and pendulums.
2. Well, the definitions are kind of equivalent - if you were at the critical angle, and you reduced the angle by an infinitesimal amount, the light would emerge into the less dense medium. But the difference is negligible.
3. If you have a standing wave oscillating at 50Hz, and you're in a dark room, and you flash a light at 50Hz, the wave would appear to be standing still because it would be in the same position every time during the light flash.
4. Some quantum **** (basically, not sure lol)
5. Prisms and diffraction gratings do kind of the same thing if you shine white light on them. If you shine white light at a diffraction grating, because of the many wavelengths of light that compose it, they get diffracted by different angles.