The rules are very simple, and very much enforced.
1] Respect the Mods and Admins. This is probably one of the most obvious and well known rules that could ever be pulled out in a community. Whatever they say, goes. If you have a dispute with one, however, do NOT make it public and drag your friends to white knight you. Contact Foedus privately for any issues.
2] If you are commissioning, please make sure you have a link to your commission rates, and your artwork. This can be in the form of a DeviantART link, or another link to a different art site.
3] Do not scam people. If you are found scamming others out of artwork or money, you will be removed, and you will NOT be allowed in.
4] Respect yourselves and others. Be mature about issues and disagreements.
5] Have fun!