What I know about your questions.

• You can post in one community and then cross post to another.

• There may be extra rewards if you post to a community only if the people interested in that community would see it and upvote your post. Rewards are a crap shoot anyway.

• Not as far as I know.

• Admins keep an eye on the posts that go into their community and from what I’ve seen they upvote and comment on most of those posts. They have authority over their community to make sure posts are not smutty and I imagine could block someone if they thought it was necessary.

The mods are assigned by the admin. Mods are people they know are interested in their community. The mods taken an interest in what is going in the community too.

I hope this helps.