I currently moderate 10 communities (though I will give most of them away once this website becomes popular: not trying to be a powermod). It doesn't take much effort, and you can always add other mods to split the workload.
You should check your "reports" section occasionally to see if anyone has reported a post, then consider: 1. Was this post made with intent to worsen the quality of the community? and 2. Does this post fit into the topic of the community? If you answer no to the second question, you should remove it, if you answer no to the first question, you should remove it and ban the user. One of the few things I like about the upvote/downvote system is it prevents the power of flooding and spamming, and makes communities almost self-moderating.
How popular would it likely be? How popular would you want it to be? How inflammatory or controversial would relevant subject matter be?
For most new communities, traffic will be low and manageable, and you can play it by ear. Start it and see what happens. Post it in the New Communities sub if you want to get some eyes on it, or just let it grow organically.
right now its a limited toolset and its a bit clunky but the subs will start small so its manageable. you really only have basic ban/block/remove post rights.