Are my friend and I able to play cooperatively in any type of custom match we want?

I just bought AoM: Extended today and remember being able to meticulously craft a custom game, selecting my opponents, the map (including custom ones), AI difficulty, and interesting game options/rules. Will I be able to do all of this cooperatively/privately with my friend who is considering purchasing the game as well?

Neither of us is really interested in the online competitive scene, just the casual "fun against the AI" type stuff.