Do I need a gasket or O-ring with this clamp?

No. V-band clamps seal through direct metal-to-metal contact when tightened properly. The conical seating surfaces create the seal without additional gasket material.

How tight should I make the bolt?

Tighten firmly until the band seats evenly — you should feel solid resistance. Over-torquing can warp the band; hand-tight plus a quarter turn with a wrench is a good starting point. Check for leaks under boost or flow pressure.

Can I reuse this clamp after taking it apart?

Yes. V-band clamps are designed for multiple disconnects. The sealing surfaces don't wear significantly with each cycle, so you can install and remove without replacing the clamp itself.