I just bought a 35 yr old apartment.  The floors are red oak.  The have a few water stains, a few gaps, and a (varathane?) finish that flakes away.  I want to re-finish the floors.  I was told to use a liquid striiper first.  This seems messy.  Will going straight to sanding only gum up sandpaper?  Do I go straight to the random orbital square pad sander?  What kind of filler should I use to fill the gaps.  What grits should I use?  When should the filler go in/on?  Once sanded, what is the best finish for oak floors?  Thanks in advance for any advice offered?

Kory