We're fostering! But now what?

I made a post a little over a week ago asking for advice on whether or not my Fiance and I should foster/adopt a cat. We decided that we would like to go ahead with fostering, but I need some info from you guys on how to make my home foster cat safe, and what things I should buy to make the cat feel safe. For context, we live in a two bedroom two bathroom apartment on the second floor. We have already decided the cat will not be welcome in our bedroom/bathroom, but it will be free to roam in the office/guest room, and the litter box will be kept in the guest bathroom. It will never be allowed on the balcony. We will be pinning all wires up away from the ground, and barricading the underside of our couches with plastic barricades from amazon to protect the wires we run underneath. What should be thrown out/deeply sanitized between each cat? What litter and food do you recommend? Do we need a water fountain? I know a lot of cats are picky with water. What kind of bed or hiding spot do your cats LOVE? Any other info would be greatly appreciated!!