I just used a random orbit floor sander to sand a yellow pine kitchen floor. Near the sink area there is a water stain and a in another spot a few boards have some blackish oil-like staining that spreads out around the nails. There are a few other random oil stains. Unless a drum sander or something else will solve my problems, I'm guessing I should replace these boards?

Otherwise, there is a section of the floor that appears darker and dirtier than the other wood overall, slightly oily but very diffused without any marks where it begins and ends. Would a drum sander remove this, or is there some product (oxy-something, bleach, vinegar, etc.) that will remove this discoloration? I think it's really going to pop out and be super obvious once my poly is applied.

Thanks in advance!

The stains are n ot likely to go away, they are probably from water damage and they rarely sand out