RE: The Hardest I Ever Worked In My Life on a Post Am I Doing Something Wrong?

Participating for a few days/weeks isn't enough on Steem, it takes a long time to ramp up to the point where you're consistently earning rewards. Many months I would say.

To answer some of your questions:

The conversion rates don't impact it at all, only that more people may power down if the price is high. SP is STEEM, 1 SP = 1 STEEM, it's just locked up. VESTS are a representation of STEEM as well, with currently 1 MVEST = 482.911, and this number increases slowly. So holding VESTS technically increases your SP holdings over time, sort of like an interest rate.
No, you shouldn't use the SBD -> STEEM conversion when the price is above $1. It converts at the price of $1, so you're losing money if you convert. There's also no 10% interest right now, there's 0% APR (as set by the witnesses).
Voting power is a little confusing, technically you can vote as many times as you want per day, but just become less effective every time you vote. The voting power display shows what percentage of your voting power remains, and that percentage regenerates at a rate of 20% per day. Each vote consumes roughly 0.5% of your remaining voting power, so when at 100%, 1 vote would bring it down to 99.5%. 40 votes is the upper limits of what you can vote with each day while still regenerating to 100% of your voting power.

Hope that helps, feel free to ask more questions :)