Can players have characters on more than one server without paying additional fees?
You are billed by account, not by character. There is one monthly fee to play World of Warcraft and it allows you to create multiple characters on multiple servers.

Will players be able to host small (8 players max), temporary servers on their own machine?
We do not allow players to run their own servers for World of Warcraft. A massively multiplayer online role-playing game demands a high level of server security and a well-connected community to flourish and evolve. We are focusing all of our networking efforts on creating such an environment.