Few questions about how rewards work on steemit

I've been using steemit for a couple days now, I've been trying to upvote and post some content, but I have a few questions that I need answered.

1. Is there any reward for downvoting a bad content? My voting power goes down when I do, and if I'm not going to get anything from doing it, why should I even bother?
2. How does the rewards for upvoting work exactly? Do I get rewarded more for upvoting before others?
3. If the same person (same SP) upvotes an article that is 10 characters, and another that is 100 characters, would it give the same reward to the two content creators ?

I have made a few searches but couldn't find detailed information on these subjects.

Thank you in advance for possible answers.