You can get as active as you want in the forum from what I can see. There are signature compaigns you need to have certain ratings in order to be involve in, but you can be as active as you want in the mean time. The more research you do, the more you will know and the better prepped you will be to make it worth wile in selling your signature.
It's ironic that this post today is what brought this old thread back from early September...and this person (number2) has no signature campaign participation but at least 20 people have since posted about this old, retired thread as a result.