Hey, @kaminchan.

Cool. I think however anyone wants to do it is the way they should. In the past, I was primarily upvoting the first comment, and if they continued to reply, maybe upvote the last one, depending on how long the conversation went. Right now, I'm still looking at how it all works so might end up upvoting a few more than just the first (if there are any).

re: minimum

Well, unless it changed with the EIP, it's supposed to be just around two STU. We've typically added a little more because over a week's time the rewards tend to erode depending on what's going on elsewhere. That small of an upvote doesn't get hit as hard as higher upvotes, though, and as I've been watching my own rewards, I don't see them falling as much as they have in the past. STEEM, though low, has been relatively stable, so that helps, and whatever other factors there may be have seem to flattened out, too.