Re: hardwood flooring
I agree with dj1, leave it to a pro if you're not proficient with a sander and know exactly what kind of flooring you have.
If you've got solid wood floors, then sanding won't be a problem, though it's still very easy to damage or destroy the floor if you don't know what you're doing.
If you've got engineered floors, then the likelihood that you can do anything at all with them is extremely low. Most engineered floors have a very thinly veneered top layer that will not stand up to any sort of sanding what-so-ever. There are a few brands such as Kahrs (Swedish manufacturer ) that has a nice thick top layer that you can get a light sanding or two out of.
If you continue forward, there are a number of different types of sanders. The most common is the barrel sander, used for removing a large amount of material very quickly. There is an edge sander, which gets along edges where the barrel sander won't go. There is a sanding screen, which is used with a typical floor polishing machine. From there you get into hand tools such as a belt sander, orbital sander, palm sander, and sanding block.
You can rent the larger machines from any good commercial rental house. The smaller machines can be purchased for a few hundred dollars or less for each piece.
If you go forward with this yourself, I highly recommend purchasing a piece of plywood to practice on until you get a feel for just how quickly these machines remove material, and how careful you have to be when using them. Final note, purchase extra sanding media for each machine you use, You will always use far more than you expect and you can return the unused portion when you're finished.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!