Some considerations also are what stores can you get to easily and your budget - there are decent foods at all price points. Your babies already have lucked out in finding a loving, caring family, so everything else will be gravy for them, so to speak. And, of course, the best food for your cat sis one they'll eat - the most expensive, organic, wholistic food on the planet won't work if they turns up their noses at it!
For myself, Nutro has worked very well, it's easily findable if you have any of the larger pet stores near you, they have formulas for all stages of life, and it's not all that expensive. A lot of people have very good luck with Authority, the Petsmart housebrand, which is very reasonably priced.
If you're in a rural area, you may be able to find some foods like Chicken Soup for cats at feed stores. A lot of people like that.
BTW, I loved their names before you mentioned the link to Toyota - and it sounds like you have a good man there, and bless you both for giving these babies a loving home. BTW, there are a lot of books out there you might be interested in (I read a lot when I first got cats two years ago) - there's Kittens for Dummies book (which is actually very good) - and I bet there's at least one staff person at your local library who's a cat person who will be absolutely delighted to help you find resources.
BTW, line up a vet yet? Any good practice will be happy for you to make an appointment to interview them and tour the facility - I can tell you you'll feel more relaxed when you know you've got someone you like set up.
Good luck - and always remember all your questions come from love, and we've all be there!