No answer for the window question as I don't have my own snake room yet... That said, I'd suggest putting in a hard flooring, like linoleum, tile, etc. Snakes can get messy sometimes and cleaning tubs, etc. can too. I'd think having a hard flooring would make cleanup and sanitizing easier. In my ideal snake room, I'd also put in a big wash sink, but I know that will probably not be feasible for me and might not be what you want to do especially if you have limited space.

I know you've probably already checked out racks, etc. But if not, look up Animal plastics and CSerpents. Both are good sources and will give you an idea on price. You might also want to go to a local show where a rack / caging vendor will be attending so that you can see how big the racks are and get an idea of how much room you will need / how to set things up. I saw some for the first time in person a couple weeks ago and they were a lot bigger looking in person that I had realized.

One other suggestion, I'd recommend having a work table of some sort (could be a desk or folding table), a storage area (shelving or drawers), and possibly some hooks (hanging storage for tongs, snake hooks, etc.). One of nicest setups I've seen was in a spare bedroom and the owner had setup storage in the closet for all of their excess supplies, cleaning gear, etc. Kept the room really neat and organized looking.

Good luck setting up your snake room!