After a match you press Y and you can invite them all to play on all your other matches.
I was having issues with lag also and it took forever to go in a match, I've noticed that its when it search for territories that it takes the longest time while horde is the fastest, elimination is not bad also but a little longer than horde.
My favorite games for this gen:
1. Gears of War 2. MGS4 3. Killzone 2 4. Halo 3(Underated by many) 5. Mass Effect