Question about Multiple Cats

Question about Multiple Cats

My boyfriend and I will be moving in together in a couple of months and we're trying to figure out how we're going to integrate our two kitties. My cat is five years-old andI've had her since she was a few weeks old. His cat will be 5 months-old when we move in together, he is a tabby. Basically we don't know what to do about the kitty litter box situation. Can they share one litter box, or is it better that they each have their own? Same goes about food and scratch posts. Also, these two kitties haven't met yet. Is it a bad idea to have two cats of such different ages living together? My kitty is fixed, but his is still too young... I'm very nervous about these cats not getting along. Any advice?