I did a little coop with a friend of mine during the testing stages of CtA. It works similar to MoWAS. Both players get command of their own number of troops that are divided equally between them. When a person spawns in a new squad or vehicle, it gives that new spawn to the player with least amount of units under their command. You're both commanders. But the game will try to keep it balanced. For missions that are set to a specific number of troops, it'll try to give both players an equal amount of control. The balance doesn't change if you go into fps or not. I took control of a vehicle under my command and when I exited that control I still had all of the troops that I had at my disposal. As did my friend when he did the same.

Sadly it's the same co-op as AS2, where units get split between both players. This can mean it's a toss up when you order a vehicle unless one player has an obviously smaller force due to losses. You can time buying stuff by making sure to stay under the CP of the other player if you want a vehicle.

I seriously wonder why you just can't have joint control over the same team. Starcraft 64 did this and did it well, was very fun having one player do economy while the other takes care of attacking. A few other games had something like that, I think I managed to create a "team" that multiple players controlled in XTA on Spring engine as well. Besides fighting to control the starting commander unit once you get engineers up that was really fun. This is the better way to do RTS co-op but I'll take any co-op over no co-op for sure.