The Lambo Gallardo does get the the Forza wing and front splitter, as does the Enzo, the TVR Speed 12, the Chrylser ME 4/12 etc, I'm yet to try/see a supercar that can't. The main cars that sometimes don't are certain classics, like the Lancia Stratos, you can give it a front splitter but not a rear wing, the Cheverolet Camaro (old ones) don't get a front splitter or rear wing but they can have an adjustable lip put on the back of the bootkind of like an old NASCAR or so I'd imagine. So it varies, but generally for the most part, thoes mods can be put on almost anything.
As for the paintshop, it works quite similar to the first one. I'm not aware of what you'r gripes we're but it is better than the first. For example being able to group layers together and save them so say if you make your own logo, you can just laod it onto any car without having to remake it. Also you can group layers and alter them all at the same time and so on. Having letters in the vinal shapes is a big plus.