I've not heard of cheat codes but i believe you can artificially lag (jump around on the screen) but i'm not telling you as it annoys the hell out of me when people do it to me. I agree there are a few glitches where people can shoot through walls. I've noticed this on headquarters on the low wall in the car park and the other night on aral sea on the fence end of the wall on right hand spawn.
I have seen people walk through walls though!