The more Steem Power someone has, the more of a reward they can give. If you get 50 votes from me, that might give you $1.50. 50 votes from yourself might give you 1 cent. Not every vote carries the same weight. That's why you can get paid more with less votes. It depends on who's voting. Don't feel left out though. Steem Power adds up over time.
I often murder my voting power voting on comments I receive in my blog, so yes, voting on comments does have an effect on voting power.
I've self voted on every post I've published. It was automatic since day one so I thought that's just what we do.
You have it right, for the most part. This part:
I shouldn't be the first one to vote for a post because I'm new? Is this right? Since I'm new me voting first will cause someone's post to earn very little. If a whale voted first that person would earn a lot more.
... I'm not really sure of.