I'm still new here so I won't try to answer all of these. So I'll just comment on SteemPower. SteemPower determines how much your "vote" is worth at 100% vote power. But as you may have noticed is that the more you vote the less vote power you have. This reduces how much an upvote pays. You regain 20% SteemPower everyday. So vote wisely. There is a lot more to this topic but I will let the experts explain it more thorough. Have fun.