help determining what these items are... (oil leaks)

Sorry you did. My bad. Looked at the pictures first.

 

If it was me......fix the separator and clean up the oil. Chances are it is oil migrating from the leak.
The air compressor can be rebuilt but Volvo wont sell you the parts to rebuild it. A shop that specializes in rebuilding air compressors can handle that.

 

@atv_idiot where are you local too?

 

you can get a spare parts kit for breather it comes filter and the gasket so you can split it away from the base they should be 10 mil bolts the other make sure to check that it's not your engine harness dripping on compressor being that there is no oil in the top half of air compressor just fed in the bottom at the compressor crank but check harness cuz it looks like its coming from top and dripping down on air compressor i have to do a d16 for this next week, also make sure you change the gasket for the breather base beiing that it always leaks bad.