All online games do client match handling. He means the clients take care of doing the match ups. CMH != Cheating. Ie CMH is where your client connects and then searches for other players to join and vice versa rather than having a server you all have to join and play. It removes the issue of waiting for a server to clear a spot for you. Each client connects to each other and then you play. Unless I'm thinking of something else.
Any fool with Cheat engine can change the values in your program and make the user way OP.
That's why you take precautions against it. I've seen several newer games that are for the most part immune to cheat engine while online. How they do this I can't say but it's being done. MMO's are pretty much always immune to any kind of simple cheat engine hack at all as the server will keeps things in check. (Never call something unhackable though. EVERYTHING is hackable if you enough knowledge, time, and effort to put into it. I'm just saying you're average bloke using cheat engine won't accomplish anything)
Because things are kept server side. When something is sent to the server, the server can tell that its bogus, and spit out errors or even ban the client. It's basic but requires a lot more work on the server.
Everything is quite the broad term. From a client-server perspective, some things are clearly impossible to hack/work around.
I'm not worried about it. Just someone having their fun for the day. Worst case scenario, admin bans me for being myself. Best case scenario, they read the posts and see I said nothing wrong, and actually I basically said what has been said by others in other threads and end up ignoring it. Taking action against me for that means they would have to also take action against all the others that have called your posts pointless.
You don't. It will archive after not being replied to after so long. Can't delete threads once they are created. So just don't reply anymore and it will eventually be archived so no one can reply anymore.