Are free adobe stock photos copyright free, can they be used for commercial use, can they be licensed under a creative commons free license?
No, they are not free of rights. Free Adobe stock assets are free because Adobe selected those pictures for the free pool and paid the licence fee to the creator. You can license them and use them according to the licensing terms.
See here and scroll down to the free collection assets:
But you certainly cannot re-license them for resale, because they have as much copyright as anything else.