I believe they are charging per bag in PHL to use the skycaps. As for the terminal you're flying out of, it doesn't matter which security line you get into. Once you pass through security, you can get to any of the terminals from INSIDE security, so you don't have to pass through again. If when you check-in they state your flying out of a D gate, remember that SW check-in is in terminal E. I always find the wait at security at E to be relatively short and if I have to go over to D, just hang a right after going through security and walk over.