Cool Larry! /forums/images/graemlins/cool.gif Wish I had some of that talent! /forums/images/graemlins/frown.gif
Don't think you can go wrong with the 3 names (2 companies) listed so far.
With your wife being "talented" she'll make good use of anything you like, but for her work, I'd lean toward dual action, bottom fed (extra volume). Just small automotive scratches, you'd be happy with single, but have no problem with either; the orientation likewise, you may find greater pressure range [check out pressure on some airbrush sites for some diverse opinions!] with a top or side mount, but will be just fine with bottom.
Finally, infrequent or remote use jusifies can propellant; but I can't pay for canned air. If you run the NPT adapter to your portable or shop air, you'll increase your investment adding a coalescing filter and a disposable desicant filter, but watch the headaches disappear; else you can always get your wife an airbrush pump so she doesn't steal your air compressor. /forums/images/graemlins/smile.gif