Well steempower gives you voting power. You can check your % at www.steemd.com/@username or with steemvoter. When people vote for you you get a % of that earning based off you steempower. The more steem power the bigger % you can get from your up votes as well as being an author. Up votes work about the same way. Its based on your steem power and also who up votes after you is how you curate rewards. I am not sure on max % you can earn from posts. I agree about facebook. never really used it honestly. I used myspace way back then before it. Guess i got over social media until tsu and steemit came around. tsu is gone though.