the riding can be as easy as you want it to be.
my 8&9 yr olds rode the greens and a few blues around Les Gets and Pleney on fully rigid 20″ wheeled bikes and had a right laugh.
I wouldn’t fancy camping after a day on the trails, its lovely getting back to a bath or hot showers then having a great nights sleep in a comfy bed..
try air b&b for accomodation loads on that site.
As for the riding, just chill out about it, as all standards go and enjoy themselves there.