Keep it simple. No dues, very few rules if any. After working in the SCCA as a Regional Executive in 1991 and 1992, I became burned out because of doing most of the work and all the rules. When I started Scenic City Miatas in Chattanooga, I made every effort not to use any ideas from the SCCA that turned me and others off. We've been going strong since 2000. Some members come and go but the group stays pretty much intact.
As for Facebook, that's a good idea. The local SCCA region as well as Scenic City Miatas and a local model car club all have FB pages. However, I would also strongly suggest a googlegroup email service or whatever service you want to use for ciommunications. Many of our Miata members have an email account, but surprisingly, some don't even have a computer. Don't lean on FB too much right away. Some of the members have computers but disdain FB