Welcome to the DIS!
I'm surprised you heard that - DCA has a LOT for younger kids to do.
Show wise -
The Pixar Play Parade is filled with character floats from all the Pixar Movies.
Your 7 year old may like the High school musical 2 parade?
Aladdin Show in the Hyperion (broadway style show) is very very well done. But if your 2 year old is at the jumpy stage there are a few parts that may scare her. You can preview it on
Youtube if you're not sure. It's 45 minutes long but you can leave easily if anyone is getting squirmish.
Playhouse Disney live on stage - a fun show with the playhouse disney cast
Attractions:
Animation Academy - This whole area is so wonderful for kids of all ages! Definitely check it out! No lines, interactive, air conditioned fun

And definitely check out the turtle talk show - your kids can talk to crush the turtle from Finding Nemo.
Monsters Inc - Cute dark ride about the movie.
Bugs Land - This whole land is great for little kids! It's themed to It's Tough to Be A Bug. The 3d show is great but too scary for the 2 year old and 4 year old. But there are a bunch of small rides in here for little ones and a water play area. (Heimlich's Chew Chew Train - slow moving "train" ride with fun surprises, Flik's Flyers slow moving up and down thing, Francis' Ladybug Boogie, Tuck 'n' Roll's Drive 'em Buggies, Princess Dot Puddle Park)
Jumpin Jellyfish
King Tritons Merry go round
Redwood creek challenge trail - play area for kids - so much fun with lots of little slides and activities. There is also a brother bear show that is very cute and worth seeing.
I really would recommend taking some time in DCA - it's also a nice break from
Disneyland when Disneyland is crowded. Another suggestion is if you are going with dh or another adult to maybe take the two littler ones back for a nap while the more energetic adult takes the three oldest on some rides the little ones won't be up for
Any more specific questions just ask!
And have fun!