Are there any utilities for this game? I'd like to be able to set up a battle and try things with both sides, a battle simulator. Is there such a thing yet? Any other utilities?

Hot seat mode in MA will do that.

Theres a scenario editor too. In it you can create any situation that can happen in a game and create a scenario out of it. You can even edit an existing one.

You need the boxed version of MA to play a scenario created like this though. It is not supported by MAN (which was meant to be primarily multiplayer).

I created one scenario that was supposed to be a sort of puzzle... you have a number of units, and you need to figure out how to manuver them in order to clear an enemy territory this turn.

You can get it at http://massiveassault.com/forum/viewtopic.php?t=325