First things first: I think I'd want to get in on a community like that. I'd like to pay forward some of the help that I've gotten with my own work, and I'd also love a place where I could beg for help with troublesome projects and have a good chance of finding someone to take a quick look. I think it might need to strictly be kept to making connections with other people for writing/reading help in order to avoid the need for formalized rules about reciprocation.

Aside from that, the only other helpful rules I can think of might be a) no gratuitous whining outside of the weekly gratuitous whining post, or gratuitous venting out of the gratuitous venting post, b) be courteous and honest, c) don't be afraid to say no or tell people you have helping you that there will be a delay, or that you're stuck, and d) don't be afraid to be specific when you're asking for help. People can always say no or bow out later on if the project isn't what they expected.

I think the most important shared value would be willingness to communicate coupled with an understanding that there will be issues and annoyances anyway, but that they'll be easier to pinpoint and sort out if people mention them. I don't know what the modding situation will be, or how much it'll be needed if the community starts out small, but a mod rotation might help to distribute the pressure of maintaining the community.