Having the AI controlling multiple vehicles can be really useful, but there should be additional commands to tell them what to do.
First: in Arma2 you could issue simple commands like "Forward, Left, Stop, .." while inside a vehicle (as passenger) and an AI teammate as driver. I couldn't find that in the current build.
Second: An AI teammate can pilot a chopper but i cannot give him the command to land, increase or decrease his elevation, ...
it might be a little bit complicated to fit these options in the already large command menu, but i think they are quite important
You issue forward / back / left / right / fast / slow commands by simply pressing those keys W, A, S, D, Q, E on the keyboard even if you're not in the drivers seat. You MAY need to be of higher rank or actual squad leader for this to work, I've not tested it, but I do know that the WASD keys work as a non-driver on the speedboat when I was the squad leader.
I just spawned in a fire team with me as leader, an empty ground vehicle and an empty chopper. I can issue commands like forward / backward / stop /.. inside the ground vehicle, but while in the chopper..
This could be added so i can direct the pilot of the chopper directly (including ascending and descending).
As mentioned: in addition to this an extended command menu would be nice...
the problem might be that this implies a complete redesign of the command menu, since it's 'full' at the moment... or you just add an additional sub menu (like for dividing a squad into colored sub teams)