Everything was going fine until the final polyurethane coat on my oak floors. I have small little chunks of urethane in the most visible area of the floor. They look like a bunch of pimples (I was hoping they were bubbles during the application--big mistake). The poly was fresh, so I am pretty certain the chunks came from urethane drying in applicator (new applicator). I am so frustrated because I have done the rest of my floors in the past without problems in the final coat. I used semi-gloss oil-modified poly. The finish also ended up too shiny (satin was too dull).

I have done some searching and it looks as if I probably need to buff and recoat. I tried samples to see if I could just finely sand or rub out the top layer, but it doesn't look right. Can anyone give me advice on the following?:
1. How do I go about buffing and recoating if I do not want to make the current poly layer any thicker than it is? Is it possible to knock-down the last layer a bit without leaving any unwanted marks or uneveness?
2. Should I use a random orbital finisher for screening, then a buffer for the rest for finer grits above 120? I am presuming that I use at least a 220 grit as I would for in between coats.
3. Is a buffer the same piece of equipment as a polisher? What pads would I use? My local rental place carries 13" and 17" polishers with white/green/black pads but no fine grit paper (I know nothing about buffing machines)
4. Is it a good idea to thin my last coat of urethane in this case? If so, what %?
5. Can I mix semi-gloss with satin of the same brand/formulation to get a sheen that is between the two?
6. Is it o.k. that I waited so long (it will be one week) to buff and recoat?

Thank you for taking the time to read this post. Any advice would be appreciated!