Thanks Amelia, that's a great request and I'm sure many others have been wondering as well. I'll be sure to cover that as soon as time allows :)
As far as votes changing value (this is my limited knowledge), the steem market goes up and down constantly which has an effect on payouts.
In rare instances someone could unvote you or flag you (downvote you), changing the final payout... but like I said this is rare. Downvoting can be misapplied, but 99% of the time, it's directed toward spammers or other bad behavior. And hardly anyone will unvote a post...
Appreciate your feedback!