I just bought a house and found out that it has hardwood floors throughout the place. I want to rip all the carpet out and refinish the wood floors. The problem I have ran into is that the old carpet pad seems to have melted into the wood floors. What can I use to get this up?

My son is evaluating a flooring situation in his house. The house has old (perhaps original) hardware flooring in the dining and living rooms that was damaged by recent tenants and is no longer thick enough to refinish again. The two rooms are connected by a wide (5 ft. or more) open doorway and the existing flooring is the same in both rooms. My son is probably going to be selling the house soon. He needs to decide what to do about the flooring in these two rooms. One idea is to install engineering wood flooring in the dining room and put carpet over the existing floor in the living room, as opposed to installing new wood in both rooms. My son is thinking of using nails with 3/8" engineering wood flooring. He said he has heard that merely installing the flooring by use of the click-grooves can result in buckling. So, he thinks using nails would prevent any buckling problem from arising. I am skeptical about use of nails with this type of flooring. The engineered wood products, at least some of them, are offered in 3 thicknesses, 3/8", 1/2", and 3/4". I am inclined to think use of nails might simply not be feasible with engineered wood flooring, especially the 3/8" thickness, because the nails would have to be very carefully installed to avoid interfering with the boards fitting together properly and the thickness of the lower lip of the click grooves might be damaged/broken by driving nails into them. Edit: Perhaps I should add a comment regarding the possibility of installing the 3/8" engineered wood in both rooms. In that scenario, the 5'-6' continuous floor connection through the arched doorway between the two rooms would result in a section spanning about 27' from opposite ends of the two rooms. Note: the boards would be laid side-by-side across that span. I mention this because I believe buckling is more likely to occur with very wide spans of flooring; that seems logical to me. Seeking experienced opinions.