Those are all questions that we do not have answers for yet. I would figure they will be much like other services that offer add - run during a show or movie, are not skippable, and will repeat.
Price is another concern, would it be free with ads, like Crackle or Pluto TV or would it be a lower price for the ad supported subscription? Knowing Netflix, if they can get something from fans on a monthly basis, guaranteed, they will go that route, ads or not.
Disney Plus just announced they are doing an ad supported version later this year. I am pretty sure theirs is going to be subscription plus ads though. I just do not see Disney doing completely free with ads. Doesn't fit their business model at all, same could be said for Netflix.
RE: Netflix Contemplating Advertising Supported Subscription Model