@darkpollo I'll have a go at answering some of your questions, until something better comes along.
Yes. Here's your reply on another server: link
Yes. I tested out creating and then deleting stuff from a remote account, and this forum acknowledged both.
Remote users don't get any privileges - their profile on this forum is just a text copy of the one they have on their own platforms. In terms of identifying local vs. remote (visually, at least), you can hover over users and see whether they have an '@' in their name. You could do the same programmatically, but I imagine that there's better ways.