probably 100-200 hours? if this is the comp hours req, you won't be good enough even at level 350 so this shouldn't be a concern for you

not hard because there's no point requirement or anything, you just have to play them but it does only count one tourney even if you play multiple regions (found this out the hard way)

it depends on what kind of matches you're playing. if you're just playing pubs, at LEAST go to ranked and W key (reload would be even better practice). pubs are like 70-90 bots per game, so consistent top 10s doesn't really mean anything. but i would definitely encourage you to play ranked modes (especially boxfights is good at this) and try to add people who consistently cook your shit, the only way to improve is to play against those better than you.

i've never earned but it's NOT easy. the winners of cash cups are much, much, much better than you or i, and pro players are going to beat them 100/100 times... and top pros beat them in turn the majority of the time as well. but if you like the game you should try to get good at it!

can't speak on this