There are no rules. Whatever you write into the contract is what they have to do. If you want your actors to show for the table read and rehearsal, write it into the contract, even if they're performing "free". You have to get them to sign a release anyway, so you can word in your requirements. If they balk, then look for another actor that is more committed.
Good luck.
Another question:
Do actors sign release after they finished the performance and got paid? Or I should get them to sign the release beforewards?
BEFORE ALWAYS BEFORE. If they walk off they can forbid you from using their footage.
Hardly any actor would do that, but who knows. Some people are crazy.
On unpaid gigs, it makes me stay focussed as everyone's time is valuable, and they're giving it to me / the production.