Congratulations and welcome to the world of cats!
And I'm SO GLAD you found The Cat Site! We'd never been guardians to cats either - and because of all the help I found here, hubby and I started rescuing cats.
DEFINITELY get your kitties vet checked every year if you can afford it. And if you can't afford it, consider a payment plan with your vet if they'll do it. So many problems that people write about here could have been avoided by having annual check-ups. Testing pH levels, blood profiles, etc. all can provide early indications of a problem brewing. Don't wait until the problem is out of control. The annual tests provide base lines for comparison for when there may be a problem in the future. It helps you establish a relationship with a vet so that when you have a problem, you know where to turn.
You're using a high quality food, so that's great. Make sure they have plenty of fresh water available. The more water they drink, the less problems you may have with urinary tract problems, common with males.
There are special treats you can purchase to help with teeth maintenance - chews that help remove the plaque. Of course, you can brush their teeth (weekly is fine). Some cats hate it, some learn to tolerate it - and some love it. Cats love to rub their cheeks - there are scent markers in there. The gland starts at the back of the mouth - and that's why some cats LOVE to have their gums massaged (which is what teeth brushing also does). Spooky goes nuts for having her teeth brushed!
As young cats, they should probably have their first dental check-up at 2. Also, at regular, annual vet check-ups, the Doc will take a look at their teeth and can let you know whether they need a teeth cleaning or not. Spooky gets lots of plaque build-up, and needs a dental every year. The other cats don't have a problem (so far).
You'll get to know your kitties and their behavior. With any noticeable changes in behavior, get kitty to a vet. One of our cats was pretty social. He started sitting with his back to everyone when in a room together. Then he took to leaving the room when we went in there. Turns out, he was very sick.
Also be aware that 85% of the time, when cats pee or poop outside the box, the problem is medical, not behavioral. If one of your kitties has a litter box problem, the first thing to do is get them to a vet. And if there ever is a problem, use an enzyme cleaner to clean it up. We use this: http://www.nokout.com/odor.html
We find it to be better than the enzyme cleaners available at pet stores or supermarkets.
For 2 cats, you should have 3 litter boxes. Scoop at least daily, and once a month bleach the boxes.
Where we are requires rabies annually and distemper... ? Even though they're indoor only.
Are you clipping their claws? This will save your furniture. It can be a bit difficult to get them used to it. We did it by clipping one claw at a time while they were asleep. We focused only on the front paws at first. It took about a year or so, but we got to the point where I can clip all their claws without any fuss (or much fuss, anyway. Treats and brushing, which they now all love, during the claw clipping is the "no-fuss" trick).
Get them stuff to scratch on. Some of our kitties love the post, some love the mat, and some love the cardboard that's kind of on an incline.
Kitties love to scratch after they wake up, so put something for them to scratch on near where they sleep the most - this will help your furniture too.
Going "vertical" is important for cats. If you don't already have something that it's OK for them to jump onto, consider purchasing some cat furniture. There are some incredible cat trees out there. Ours are designed in green and brown - like trees with tree houses. We love the way they look, and the kitties love using them.
Welcome to the world of cats!