To keep the account active, you only have to log in, but posting in the community is always appreciated as it's kind of like giving back to the company. It may not be money directly, but with posts and ads that are displayed it brings in money and even members to keep the place strong. As for getting your account unsuspended, you can click the "Request Unsuspension" link on the top left navigation bar to unsuspend your account. Posting will not unsuspend it.