I am not quite sure if I understood your question, but I think that the answer to that is...you do not have to post necessarily important things on the forums to stay on the free hosting plan. You do not even need to post at all. You just have to LOG IN every two weeks, as a measure to make sure that you check the announcements and so on. If you DO post, you can post about whatever you want, as long as it's in the right section and is not spam.
Speaking of which, I believe that this post was in the wrong section =/ I'll close this now. I hope that answered your question.
~~B3N