Support Forum

I'm referring to the basic forum that's on my site.  I'm currently using the latest version of Simple:Press for WordPress. I love the back end where I can easily configure the permissions and etc.

I signed up for the Silver and I'd like to quickly get going on the forum. I don't want it to drag on.  I do need help in better structuring the forum both forum wise and skin wise. Here are my goals for Inspiration Point Forum:

First, I want to create two distinct group forums. The first is a private group called tentatively Shore Classified. This group is directed at the churches in my region, Jersey Shore. The group will consists of multiple forums catering to different need.

I'm using the classified section of the newspaper as a model of what I'd like to do. One forum is for businesses who'd like to post an advertisement for their business. I really don't want to do free advertisment. I do have a goal of earning some money with my site.  Any ideas?

The second forum is a "Help Wanted" and this is the forum that needs to be private. I am imagining someone will need to post either a phone # or address in this section. I don't want this exposed to the public. I'd like to limit this to members of that forum.  Any ideas of how?

As a blogger, I know and understand the need to share about your latest blog updates. I'm also supportive of many local Christian bloggers. I'd like to create a forum where they can talk about blogging, writing or related items. It's only in the Shore Classified because I know some of them. This can be expanded.

The second group forum is open to the public.  Right now, I want to use this as a way to draw traffic. I'm not sure of what to put.  My site is spiritual and about encouraging people.  I'm considering adding topics like a gaming forum, politics, Christianity and etc. I'm only vague because I'm not clear.

Ideas please??

Here are my more technical questions. How do I keep one or more forums, private? How do I encourage guests to participates, as they don't seem to be in a hurry for membership? I did tweak the guest permission to allow replies to existing topics. 

I'd also like to track down a good theme for the forum on my site: http://inspiration-point.org  I didn't put this at the top; as I didn't want to appear to be spamming. I'm serious about my questions.