I was wondering how people make use of the Astromench Droid? Its only use seems to be to repair vehicles, but as far as I can tell, you can't actually attach one directly to a vehicle unit. Nor can it move around independently. So you would need to attach it to an infantry squad and then keep that squad close to the vehicle you want to repair? Do i have that right?

Right you are.

So how are people using the droid? Or are they?

I've used him a few times with the tank and some snow troopers. It's nice when you can remove the damage token and keep a badly wounded vehicle operating at full effectiveness for another turn or two.