I answer all 3 questions.
1) Many scenario. Married deal on agreed price. Like A sell to friend as market no liquidity to absorb his quantity and he dun wanna depress it so do married sell at lower price. If A dump open market the stock will crash.
2) Buy up? Sometime to mark stock prices. Some funds to it to beautify the books on some of the shares they own especially during month end window dressing. Some do to prevent margin call. Some do to make technical chart nice.
3) Fake queue. Trick you lor. Assuming you Big boys, if you really want to sell, you will not want to queue big quantity to scare buyer. Usually they put it there to make people sell and then they collect. Once collect finish they remove fake queue and buy up. And give versa