Se non ricordo male si fa parte del parco la terra dai sette colori

You can not go down to the waterfall. There is a parking lot right by the Viewpoint. From there you can walk around, 5-10min.

No Idea either.

Nous n'avons remarqué aucun accès permettant de descendre s'y baigner, le lieu a l'air d'être un espace protégé au contraire. Vous nous direz si vous avez pu y aller ^^

Hiya! I don't think that both these activities would take a whole day, but if you include travel from flic en flac then maybe it maybe a half day tour. Most of the sites which are on tripadvisor are in the south. Tour operator should be able to best advise how to combine activities to get the most out of your day. Hope this helps.