I'll do my best to answer ;)

A). All votes are done at the Steem layer initially. This means that ALL voters are ranked in the same order and aren't affected by the tags. Think of it like this: 50 voters vote on a post and each are ranked 1-50. After they've voted on Steem, SCOTBOT searches their Steem account for staked Tribe tokens that match up with any tribe tags used. Some may have stake, some may not. if you have stake, then you're put into an additional line for that SCOT token which goes by the same rank as the Steem upvotes... Kind of a compkicated way of saying that the "order" is the same on Steem as it is for all tribes. Some people earn and some don't and that's just based on stake.

B). There are graphs floating around. Some were done my Steemit. Others were done elsewhere. I forgot where at the moment, if I remember, I'll edit them in.

C). Probably would be a good idea :)

D). Not yet. I believe Steem Engine has said that they're still working on being able to split rewards and identify what's from mining, curation, author, etc. For now, you gotta just use the Steem Engine block explorer to search for rewards (but they're all under the same identification "issued")

Hope that helps ;)