Hi Kevin. I have an M370 and have often wondered at the funny design of the filter tray. Mine has two tiny, tiny lugs at the front and the same at the back. You have to be very precise when you cut the filters otherwise they wont go in or they'll fall right through. I made a cardboard template before I cut mine.
Sorry I can't help with your other query, I'm pretty much a novice.
Good luck and I hope you enjoy your first printing experience. It's addictive.