You land at 10:30 and your next flight leaves at 12 or 12:20? Remember, most flights these days board 20-30 min. early and sometimes the doors are locked and they are pulling away from the gate at the stated flight time. Personally, I don't think you will be able to make it off your flight, go on the tram back to baggage claim and the main "pedestrian area" with the restaurants, have lunch, go back through security, get back on the tram, and finally find your flight again.
If your friend could meet you as you get off the plane and then eat in that terminal (there are many places near the gates), without you having to go through security - that would be different. The way security is now, I don't think they allow anyone without a ticket to pass through securitiy and go to the terminals. So, If it were me, this lunch with a friend wouldn't be happening. Sorry.