I used to power level in delta server but then they removed it. Now i heard about spy hunt.

I heard that each person (5 people) gets one intel and you just waste your time after you get the intel for the whole game that is i think 12 min. My question is how much exp you get for it? and is this good tactic to powerlevel? Any other suggestions appriciated.

THanks.

And offtopic question: How do you know if a GM is in the game?