What species of wood floor do I have?
Poly will wear faster than a standard floor urethane product. Stain color is your preference. Any stain will work on any wood. If you want to compare stains on wood, visit a store with stains, they should have a sample chart with different wood species and show how the stain absorbes into each one. You will need to sand the floor completely with a floor sander before attempting this work.

More info on hardwoods used for flooring