Hi acinonyx,
The Disney official website is not brilliant, so with so much to absorb, I'm not surprised that your head is spinning! You are doing the right thing by planning ahead, as so many people do not, then don't get the best out of their time there.
You do not say what dates in August you are there - this can make a difference regarding crowd levels in the parks, as some dates are Francilien Annual Passport Blockout dates. This means that local people ( and others ) who have these APs cannot use them, so are less likely to visit the parks as they would have to buy tickets.
July / August in resort is known as Summer Time, with longer park hours. Generally, Mondays and Tuesdays are the busiest days along with the weekend. Wednesdays and Fridays are usually the least busy, and Thursdays can vary.
Fantillusion electrical parade at 10.25pm usually, followed by fireworks over the castle at 11pm. Ride entrances close at 11pm. Shops and some food places in the park stay open for a while longer. Once Upon A Dream parade with the large floats is usually on at 7.15pm. You will see Princes and Princesses on their floats in both parades.
Disney Dance Express Train will go down Main Street at set times during the day, and Characters get off the train at central Plaza to dance, and invite kids to join in.
The Tarzan show has just returned to the Chapparal theatre in Frontierland, which is a very good show to see, with singing, dancing, and it should include some aerials.
With four separate Lands, it is important to choose rides that your daughter will enjoy, and not be scared. Some kids are very frightened by Snow White ride, as it focuses on the wicked Queen and dark woods. Do the Pinnocchio ride next door first, and if she doesn't like that, don't do Snow White. It is also important to do gentle rides first to build confidence - if you do something that scares her first, she may not want to try anything else.
Some kids are braver than others, and like more thrilling rides, or dark ones.
The park gates open at 8am for Disney hotel guests to go on selected rides, whilst day visitors and other hotel guests are restricted to Town Square and Main Street from 9am to 10am, where they can look in shops, or buy food/ drink in some places that are open early. At 10am they are allowed to access the Lands for rides.
If you look in the Top Questions list on the DLP/ Marne La Vallee forum page on Trip Advisor you will see one about rides for young children, which also gives the height requirements for rides. People on this forum can help you plan your day to get the most out of it, with your child in mind, and give you helpful links for ride descriptions and other info. There is just too much to write here!
Both forums are linked, so you can use either one, and read both pages of Top Questions.
www.tripadvisor.co.uk/ShowForum-g226865-i2224-Marne_la_Vallee_Seine_et_Marne_Ile_de_France.html
www.tripadvisor.co.uk/ShowForum-g2079053-i21935-Disneyland_Paris_Marne_la_Vallee_Seine_et_Marne_Ile_de_France.html
Regarding the Studios - High School Musical is only represented in Blockbuster Cafe theming ( the other half of the restaurant is themed with Pirates Of The Caribbean.) There is nothing else to do with HSM in the park - this was a previous year's show.
Things change every year in DLP, and also during the year with the different seasons. There are very few ride closures in Summer Time, if any.
There are some things in the Studios that your daughter will enjoy -
Playhouse Disney ( theatre show )
Stitch Live ( theatre show )
Animagique ( theatre show featuring Mickey, Donald and other Characters from Disney animation movies ).
Flying Carpets over Agrabah ( like Dumbo elephants ride, but usually a shorter queue ).
Slinky Dog Zig Zag Spin ( very tame, in Toy Story Playland ).
Cinemagique ( cinema film with a twist.....)
Art of Disney Animation ( two theatres, one showing Disney animation film clips, the other features Mushu, the dragon from Mulan on screen ).
Toy Soldiers Parachute Drop descends slowly, but depends on whether the child ( or adult! ) is afraid of heights.
Sorry - have to dash - am at work!!