That's wonderful news! You'll have a great time :)
Please PM me if you have any questions, i'm a Disney nut 
Newport Bay has a lovely swimming pool. When are you going? It's lovely strolling along the lake in the evenings.
Don't forget to bring a doctor's note for the girls, take it to guest services at City Hall and they will give you a special pass so you don't have to use the normal queues and can wait in a less crowded area.
If your girls want to meet a princess you'll need to get to the Princess Pavilion at least 15 minutes before it opens (usually around 10am I think). Because you are staying onsite you get to go into the park before everyone else (like us who are staying offsite lol). This is a good time to go try the rides that usually have longer queues like Dumbo (its a slow loader as there aren't that many elephants1).
Cafe Mickey is a great character restaurant but quite busy. However if you go there for breakfast its quieter. I know you get breakfast for free at the hotel but we just decided to pay for the character breakfast to have somewhere quiet to relax, enjoy our breakfast and for our daughter to meet a few characters without kids being pushy etc.
Annette's Diner is a fun place to eat, great music, waitresses on roller skates and nice burgers.
Auberge de Cendrillon is a princess character meal, posh food in a posh restaurant with lots of princesses and their princes having a 'ball', dancing etc. It is ridiculously expensive and i'm selling like mad on ebay currently to afford for all 5 of us to go next month (over £200...its outrageous!). Because its very expensive it probably won't be full (photos i've seen of the restaurant that friends have taken always seem half empty).
If you love coffee you'll find it a bit dire at DLP however Starbucks, bless them, opened up in the Disney Village :) There is also a great toasted sandwich shop there called Earl of Sandwich, very yummy.
If either of your girls have problems with loud sounds I would bring ear defenders for them to wear during the show 'Animagique' which is a brilliant stage show but very loud, especially if you are sitting next to one of the speakers. I'd sit in the middle near the aisle. Don't worry if anyone in your party doesn't like being in the dark or the noises etc from the show, there are staff there all the time with small flashlights who help families out who want to leave during the show for whatever reason.
Oh, beware the moorish Mickey Brioche...its gorgeous and filled with Nutella!
I can't wait to go now...only 5 more weeks for us! Have a fab time xx