I use a simple home made catch can an all I've had out of its is a bit of water. I don't bother with the pcv valve as I'm running ITB's.
Engine breathing is very simple, its amazing how many people get confused by it.
Only if fitted by the factory. Most pre 92 cars won't have one
If you can pass the emissions test without one ( nearly impossible) on a road side test they won't be interested why its not there