I know there are servers with chat filters. Maybe a head admin of WNx or other servers can shed some light for you. I'm not home this weekend so I cannot effectively test any systems(working from phone/CR-48).
I've never tried/looked into a no camp plugin. Nor seen one on a server. GE:S built in anti-camp isn't the most effective system, but we cannot down a player for using strategy.
As far as the servers not showing up. This is a problem on about half the player base. We also cannot change valves server browser code, its there bug, and its hurting us. I don't remember anyone during development mentioning not being able to see our testing servers(then again, when we used the server it had people in it). So we couldn't foresee or look into a hack to fix it.
There are ways to cheat and fake players, but we don't really endorse that, so will have to research yourself.
Thanks for the work on hosting a server. If no one is able to help you before Monday, ill be home then and I'll see if I can help you.