I can not help on how long for 2 people as we always have 4--usually do 6 rows at a time, repainting floor as we go along.
I can tell you as far as removal I have the best luck just using a good ratchet wrench and over tightening the existing bolts which in most cases breakes them below the floor line (they usually break off anyway trying to loosen them---but leaves a piece above floor that has to be ground down).
I also learned my lesson fast on using a lower priced hammer drill---get a good industrial one and you will save a headache--and your back
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