Need help identifying valves and pipes...

Hello all, this is my first post and my first pool as well. We bought a house in a bank owned, As-Is situation and it happens to have a huge in-ground swimming pool. Problem is, I don't have any idea what is what! If anyone could help me identify which pipes and valves are for what in the pic, it would be hugely appreciated.

I know its a Hayward pump and a Clearflo DE Filter, but more specifically I'm trying to identify the main drain, the skimmer returns, and the waste line and how to open and close the skimmers.

In the front of the picture, there are two sets of upside down, u-shaped pvc pipes. The one on the left (picture left) goes into the pump and the one on the right comes out of the multi-port valve, both sets of pipes go into the ground. I'm assuming one of the sets is the skimmer, and the other is the main drain? And then the pipe in the background on the far left is the waste line?

Also, the u-shaped pipe going into the pump has a red valve on it that seems to be stuck in the open position. I can budge it a bit in the closed direction but I'm muscling it pretty hard and I'm afraid I'm going to break it. The valve on the other u-shaped pipe (coming out of the multi-port) will spin around and around. Are these broken or is this normal, and do one of these valves control the skimmers?

I appreciate any help! Thanks!