Can I use a factory AC / heat dash switch set up for adding aftermarket AC to a factory non AC car. I like the "factory" look. Or do I have to use whe switches the aftermarket unit has?

The Classic Auto Air setup for '68-'70 B-body uses the factory slider switches. You only have to replace the contact switch inside the unit with one of theirs that they provide. Factory look is retained.

What car are you going to put this in? I know on the 68-70 B bodies they have their own controller. It looks pretty good, if you're not too hung up on the factory look. If you have heater controls, they have an option for that too. I'd hunt around on their website and call the tech line.
I do have their system in my Charger. It's pretty good at keeping the car cooled off. It's by no means as efficient as the r-12, but it is ok.

Sorry, I should have had it in my original post. This is in a 1970 'Cuda ralley dash.