Some Friendica advice please

So, as I've already announced, or rather another me announced, we're planning on shutting down my Mastodon instance in the future, and switching to a hosted #Friencica and prolly merging this account in there too.

I do have some questions about how to set up accounts, my Mastodon currently has five:
admin
personal, because you never run as root
taurnation, art & link sharing group
recalls, link sharing group
Xnews, stuff related to my work

So, the question are

  • How to do this on Friendica, is there any difference between additional account and creating a new user?
  • How exactly does a community blog work, as taurnation and recalls might be better arranged as such, that way others can contribute.
  • How can one theme, is that server side only? And how does one create a theme?