I used to adopt my cats one at a time. This last time we adopted littermates. That being said, Yes you do need 2 feeding dishes and 2 litter boxes. germanquilter is correct. What she does is what I have learned from research and experience. There are going to be some cats that are accepting of other cats and some that are not. If you are adopting from a rescue, they should be able to help with matching personalities (I hope) and maybe a test visit between the two. Absolutely, make sure both are neutered. Unneutered animals are very territorial - male or female.
Good luck. Most cats are more social than people think and will enjoy another cat being around. It just takes time.