Yeah negative camber was never something I had a problem getting, part of that is the lowered ride height. Positive caster is harder to come by. But even adjusted for max positive caster I usually still have plenty of negative camber. Those shims might be a good trick for going autoX'ing, bump your negative camber from a streetable -.5* to -1* to a race only -2.5* to -3*. But to get into the range needed for a street car I don't see them being necessary.
Yeah that's fine unless your toe is off by more than just a hair. It doesn't even take that much toe (in or out) to wreck a set of tires in short order.