I run a high end,high volume body shop for a living .Waterbourne paint has been around a long time,been used in Europe last 10-20 years. Anyway the base (color) is basically the water part,and the clear coat is a low voc paint,still has solvent,but a lesser amount to meet regulations.
Painting with waterborne is easy, yes you need a slightly different setup,air driers (waterbourne dries by air flow, by air blowing over whatever it is that you've painted).
You can paint over pretty much anything with waterborne,the surface/car etc is prepped exactly the same way you would with any other paint etc.pretty straight forward ,same technique to spraying etc, just mixed diffently, any competent painter can do it no problem, I have 4 full time painters and they all love it,wouldn't go back ,hope this helps........