PVC is good enough & cheapest material for the above service. This can also withstand quite a bit of pressure.
Yes, SS (whether 304 or 316 ) totally unsuited for above service.
In case of PSv discharge is to atmosphere isolation valve at outlet is not required. If discharge is connected to flare / relief header yes there is need to have isolation valve at both inlet & outlet sides. However there is need to interlock the isolation valves such that at least one of the...
I do not think this is something that can be done at home.
You could try EDC or Methanol. These would, I guess, extract many other things (pigments, proteins, etc. ) along with component you want!
Separating these ingredients would be a tougher exercise.