Yes, they are playing, you just need to have XFire and give people a shout. There are plenty of XMP players around that would like to play, but they can't due to empty servers - that's where telling others that you would like to have a match is beneficial since players are guaranteed.
Alternatively, you could join a server and wait for a while. People often notice you and join.
Clans, not so much. At least I haven't heard of much activity from them.
The forums are active. Not as much as others, but enough to answer your questions.
And (GR)Killer is being pessimistic