Hi, I've not stayed in La Plagne so can't comment on the specifics but on a usual Esprit holiday there will be no movies on the coach. We take ipad/Amazon fire/Sticker books and wrap a few tiny present for them to open on the plane/coach (think mini notepad and pencils, matchbox car, kinder egg etc) which usually keep them entertained.
On arrival at the resort Esprit staff will meet and greet then escort you to the chalet/hotel sometimes this is via mini bus, sometimes the mini bus takes the baggage and you walk the short distance and sometimes you and the luggage walk the short distance (esprit staff usual drag the cases while you try and control the kids).
With regards the lessons, give esprit a call and ask them what the ages of the other children will be in Sprite improvers. In the lessons they will have a snow ranger with them who usually take a drink and biscuit along which they can have when they have a short break. We usually put a small chocolate bar (milky way) in their ski coat pocket which can have instead if they want it and i would say this is a good call. Make sure they have a small tube of sunscreen and lipbalm in their pocket too, you can get a combi tube which is great.
I would label all clothes.Take a small drawstring bag and on the evening pack all of their smaller ski school essentials (gloves, buff, goggles etc). I think esprit give you one, I can't remember if that's just at nursery though. Mornings can be quite hectic so it's great just to pick up the bag and go.
Make sure you take a photo of your lift passes when you get them, if you then misplace them you don't have to fork out the full amount again.
Enjoy!