I think it's preferable to go by train, they have really nice and comfortable and rapid trains that take you from Paris Gare de Lyon to Cannes Gare directly. I don't see any way of going by plane but you can do your own research.
For the parties, the best way to get invited is Money.
Thanks for providing so nice information. Who on earth cares about tablets when all the fun is in Cannes, the beach, the parties, and of course the beach parties...
Do you have any idea if there still are hotel rooms available ? I'd rather not go if i can't get a decent hotel room. And do you have any contacts that work in the bakery field, i would need some premium quality flour too.