I agree with the other posters but would like to make another suggestion. I recently refinished hardwood floors in my 75 year old house. They had been stripped to bare wood with a drum sander about 10 years ago, and all I wanted to do was rough up the finish so that the next coats would adhere properly.
We 'borrowed' a sander from our local Home Hardware dealer (Canadian, eh!) Basically it was an orbital sander but the pad measured 18" by 24" and the machine head weighed in at 130 lbs.
You want to talk about slick. I sanded off finish in about 750 sq. ft of floor in about three days at a couple of hours daily. The sander was marketed in a display by the Varathane company. You may be able to track one down in your local area. AS for the finish, I used oil based because that was what was there before. It's difficult to get finishes of different types to adhere to each other properly. Good luck! Grant