a stock manifold is cast, some after market upgrades are cast aswell. But you will see alot of aftermarket stainless steel manifolds which are supposed to flow better. However alot have the tendancy to crack under heat, have weak welds.
a standard 3 bar fpr should be fine with the injectors i mentioned. I spoke with my tuner about this at the weekend and thats what they advised.
The pcv system is the breather system, if you use the search option you will see alot of people have problems as the standard rubber pipework over time comes weak and splits, causing various things inc loss of boost. The engines are heavy breathing engines and the vapour goes through the breather system and back through the intake system and build up at the lowest point i.e intercooler.
One way to improve the breather system and minimise oil build up in the intercooler is to fit a catch can into the breather system