1) I've never seen any report or study making this claim. You are making it up.
2) A very few athletes do what you claim, and are highly reported on. This is not due to Nike, but the way the press and public idolize athletes. Most never do bad things.
3) No, they weren't except in track and field. Football was momentarily improving, but would never have remained competitive on a regular basis. If they did not have the facilities Knight helped them build, they would be the league doormat or maybe not even still be in the PAC-12. All the other non-revenue sports that are so good now would be horrible or nonexistent. UO would not have grown to 24000 students, maybe would have diminished below the 17000 they had. The entire city of Eugene would be poorer because the UO is a major economic engine.
4) Not in the countries they contract in. Like Indonesia. In 2013 Nike employed about 171,000 mostly in poor remote areas. Nike goes there because of plentiful labor.
5) Successful, not greedy.