Site for volleyball air pressure and bumps??
Another factor in air pressure is age level of players using the ball; balls are softer and have lower air pressure for younger players than older players. Generally for most volleyballs, ball pressure is 4.3 - 4.8 psi, and a sports air pressure gauge will be able to tell you the air pressure of the ball being checked.
Air pressure for some volleyballs are usually around 4+PSI. But brand/model of volleyball might make a difference. Bumps? As far as passing/bumping the ball? What do you need to know or want to know? http://iml.jou.ufl.edu/projects/Fall08/Devine/passing.html There's many sites, and several techniques. Youtube will also provide video documentation if you need.