Re: what does bump mean
People 'spam-bumping' is the entire reason they put a one-week limit on bumps there. You can still reply to older messages, they just won't get rotated back to the top of the list until there's a reply AFTER the one-week time limit.
And there are two different methods of 'bumping' a topic...one is to actually take the time to compose another message, sharing new (and hopefully relevant) information and updating details from the original post.
The other is to just type 'bump' (or anything else, really) into a reply. The system registers that as a new response and rotates the thread to the top of the list again. This is, by far, the more common option in something like 'Wanted: Players' or similar threads, because the original post has all the relevant details, most of the time.