(No, the roleplay part does not involve anything sexual or other dirty stuff but rather creative, collaborative writing with SFW-only content)

This might sound like a strange or even insane idea but I'm planning to extend our website, which has a RP forum, Booru and Wiki already and focuses on roleplaying in a fictional, self-made world. Said world is Fantasy but there are also some high-tech technologies like the Internet, so I had the crazy idea to make an in-character social network where players create accounts not for themselves but rather their various characters that basically use a fictional social network that exists in said world.
So, I'd like to now if the following things could be coded in, are already there or are otherwise possible:
- Make it so that new accounts have to be approved, so that some random people outside the forum can't make accounts. Only people I know from the forum should be allowed to make accounts. Alternatively (or additionally) making it so that you can only reach the site if you have the link
- Remove anything related to real sites like Facebook, Twitter and co. Theses sites don't exist in that world, so they should also not exist in the social network. Stuff from Oxwall regarding copyright and anything else that is needed can stay, of course
- Remove any dates completely. They use a different calendar and year, so the real date wouldn't make much sense. There is no need for a replacement, just completely removing anything date-related is enough
- Making it possible for one person to have several accounts and make it so that they can easily switch between them (for those with multiple characters)
- Giving the admin the possibility to artificially alter the follower number of a site. Since only members of our forum are allowed to have accounts, the follower count for fictional profiles like a news site would be small so I want to put a fake number there for immersion
- Allow a fictional country and other data to be used in the profile of a user (if that isn't already possible)