If I can remember correctly after you collect the pods, a number shows up on the tv which shows how far (in meters I think) you are from the entrance. When it goes up you are going in the wrong direction. When the number decreases you are going in the correct direction.
I can't remember so well but is this after you fight Croc or not?
Sorry, I finished it quite a while back & I cannot remember so well.
Correct, it's the same way that you found the pods. Batman places a device at entrance and after you've found all the pods, you just need to go in the right direction and let the distance meter count down.
Good to hear dude. When you finished, get yourself Uncharted 2. Don't be alarmed when your cooling fan goes into "TURBO" mode, it's normal, just doing its job.