u/TheSultanOfStink

Took off the carpeting and found the floorboards to be in pretty good shape.
My only experience with flooring was sanding and staining another room with the same boards and finish that was uncovered and water damaged.

Best practice for cleaning up and refreshing?

So far I figured id rent a home depot polisher, hit it with red pad, then white. Not familiar if I need a solution, water, or dry for this case. Or if a product should be applied after. wet look? Wax?

I added fine trim screws flush to surface to try and eliminate boards from squeaking

Last thing is the black tar (?) and crud in the gaps. Would it be reasonable to meticulously apply black caulk flush in the gap to seal in that stuff and eliminate the gaps?

Opened up some floorboards in a two floor office type building being remodeled and screwing down all the squeaking boards. Being totally optional, would it be beneficial to blow in cellulose for sound proofing or as interior insulation? I plan on densepacking an adjacent partition wall for noise control. The ceiling is plaster lath with another layer of drywall so the mass is there to deaden speaking noise fairly well...