Hi, welcome, & congrats on the new kittens! I'm glad to hear that you have 3 (instead of 1) because they will keep each other entertained and will burn off energy easier.
Feeding twice a day is not enough for kittens. Either free-feed or give them at least 4 feedings a day, maybe even 5. Kittens have tiny stomachs but need lots of food. What I would do is leave dry food out at all times but then give them as much wet food as they will eat twice a day. I would vary the wet food brands so they don't become used to just one food (it will be easier on you in the future if they aren't picky about wet food). Make sure they have fresh, clean water at ALL times, not just when they eat. I never free-fed my kitten (who I adopted at 12 weeks old) because I didn't want my older cat eating her food and I couldn't keep them separate all the time, so I fed her at scheduled times 4 times a day.
Science Diet = junky food. There are much higher quality foods and they aren't necessarily even more expensive. Science Diet's dry food has byproducts & a lot of corn. For easy-to-find and not expensive kitten dry food, I would try Nutro Natural Kitten or Nutro Max Kitten (PetSmart, PetCo). Royal Canin Kitten is another great option that is easy to find, I think it's a tiny bit more $$ than Nutro. Authority is PetSmart's own brand and is very similar to the Nutro brand, ingredients-wise, and is a little cheaper. Blue Buffalo Spa is easy to find and they make a good kitten food I think too. Also, there is Wellness Kitten & Chicken Soup Kitten which are very good but you won't find them at chain pet stores, you'd have to try mom-and-pop type places.http://cats.about.com/od/catfoo1/tp/kitten_dryfood.htmhttp://cats.about.com/cs/kittencare/a/kitten_food.htm
Are they spayed/neutered yet? If not they should have that done very soon
Sadly, cats can reproduce as early as 4 months old. (just thought I'd throw that in).
*runs off to see pics*!