I agree with what Slick and Caffeitina said, but also, think plan what you're going to do when you go on vacation... do you have anyone to look after your cat, or will you need to put him/her in a kitty hotel?

Concerning food, I'd give the cat food you buy at the vet, that is the most healthy and may prevent your cat from getting sick in the long run.

When you get the cat, make sure you have lots of time to be with her/him, especially to begin with.

Good luck finding the one/two for you!