Is the CAN bus protocol a master and slave protocol?
A CAN bus is multi-master and automatically arbitration free. The whole point is that you don't need a single master or main controller to take care of everything. Each message that is sent has a priority, and higher priority messages trump lower priority ones (a lower priority message will wait until there isn't a high priority message being sent). So there are no slaves. It's kind of similar to a peer to peer network, in that it's decentralized. The reason this is done is to reduce failure points. If a single main controller failed, so would the entire network. If there is no central controller, a single component can fail and the rest of the system will keep going. 

For your network, you should assign priorities to each command sent depending on what's most important. The Wikipedia article is actually quite good.