Usually a good painter can just look at the paint and be able to tell if it is oil based, but to test this out you can take some denatured or rubbing alcohol and try to remove some of the paint. If the paint is easy to remove, then this means the paint is latex. You can paint over the oil based paint with acrylic paints as long as the surface is dull and clean without primer. Primer is never a bad idea though, especially if the sanding is questionable. I'm not that familiar with SW, but I believe Pro Mar 200 is more of a wall paint. Perhaps Pro Classic would be better for trim.

I agree with paintguy, a good painter should be able to recognize oil or latex. I always sand & prime, but that's me.
As for the wall paint, any surface with a sheen like a semi-gloss is perfect for glazing or many other faux finishes. If they are picky faux painters, they'll probably prefer a specific brand/finish, but what you have will definately work. I wouldn't, however, use wall paint for trim. Like paintguy said, use a trim paint.