Regarding posts that have a lot of votes, but are hidden:

If you see posts, that you think are junk or spam then you can disagree by down-voating/flagging the post. Just like someone with a lot of Steem can add a huge reward to a post with 1 vote, that same power can be used to flag instead. Steemit.com chooses to hide posts that have low ratings as a spam and copyright protection measure. This doesn't necessarily mean that other sites based on Steem will hide it as well and with a bit of time you can technically set up your own Steem interface that for example would not hide flagged posts of certain people you want to whitelist. That's why it's "uncensorable" once a post is on the blockchain it "can't" be completely deleted. And the Steemit.com website is also open source, so you can copy it and make your version do whatever you like.