Re: Refinish, Replace or Deal with it?
for a house thats 100 yrs old thats pretty common, over the years the wood has gone through so many warm and cold seasons that it will move eventually opening up as you describe.
if its really bad simply sanding the floors wont do anything other than give remove years of wear on the face of the wood, then the other thing would be to fill all the cracks with filler but that doesnt always give a perfect color match to the species. all you can really do is deal with it or replace the floor.
as for the draft the big thing there is to get insulation in between the joists to stop heat loss and air movement
fire up the saw and make some dust