Newbie Questions: How Do Resteemed Posts Get Rewarded?

Hello Steemit community!

I have a question regarding resteeming. (Note: I do not intend on resteeming others' content except in rare circumstances -- and that was my intention even before I read the etiquette guidelines.) On to my questions:

1. When a user resteems another user's post, how are the rewards for upvotes allocated? Is the resteemer considered a curator, and any upvotes etc. get allocated to the original author's post, or is there some other mechanism in play?

2. Also, do upvotes alone determine reward allocation, or do comments and resteems also contribute? How are they weighted -- the same, or do comments and resteems count for more or something?

3. At the end of each payout period, if an old post continues to accrue upvotes, can it receive an additional payout during the next (and every subsequent) cycle? Or, can each post only receive rewards for the first cycle after it is posted?

I apologize if any of these were answered somewhere already, but I read through the FAQ comprehensively and couldn't find unambiguous answers. Thanks in advance for explaining! I have been looking forward to this concept for a forum for years, and I'm so glad it finally exists!