I can't speak to the CT control at all, but I would be very leary (sp?) of a machine that you cannot verify the accuracy on. Not saying the guy is crooked, I am just no longer a trusting person. Just getting this machine moved and installed is going to cost you a bit, and if the repair of the Z homing issue doesn't solve all the machine's woes then you'll be in a bad spot. I'd get him to repair the drive first and prove that's all that's wrong!
I've had many of the Arrow's of several sizes all with the A2100 control, and most have been maintenance intensive. You should be fine on air for now, the only thing that uses it is the drawbar and spindle blow out, and if it has linear scales it will use a bit for purge, and some of the Arrow's have a spindle lubricator that uses a small bit of air.