How NSFW is handled by default can be changed in your user settings over at steemit.
Id assume this will either soon apply on dtube as well or it will save your selection id hope. It might even a be a bug that it doesnt apply crosssite.

Yeah, censorship wont happen. Yes, it might not be promoted as heavily if its downvoted by a whale, but that also drives down their voting power, and in effect its how you make money, by selling your steem$ to someone who wants to do it. I mostly looked at subscriptions on youtube anyways, id assume it will eventualy be very similar here as soon as enough people will be using the platform. Also, as the entire community accumulates more steem this will become a smaller issue. But the actual contributors(that includes comments and the like), at least the ones which are upvoted, will allways be in total more powerful as at least 50% of the steem is put into your voting power, you cant sell that 50%.
So, while you can "manipulate" it via buying steem, this same fact also rules out the use of votebots. You cant just create hundrets of accounts.
And many votes very soon will decrease your voting power, so even then you cant just go around and downvote a lot at near full power.