This guide is looking good! It's true that knowledge is pwnage!
As for camping, like everything else, it has it's pros and cons. If someone is whining about people camping it's probably because they're either too lazy to develop a strategy to lure them out, are constantly owned by it, or simply don't have the guts to try it themselves or counter-measure it. That's why it's good to have a balanced team. A team full of Creepers can camp in teleporters, but that will just get the humans looking at the floor all the time...
Myself, I camp sometimes, I head in the middle of a fight sometimes, and sometimes I run like hell blasting crap. Whatever suits the situation.