Sounds weird that it wasn't allowed. It might be a site specific reason, as I have gotten it changed in the past.

The slug is one of the issues as to why you can't create a user with special characters, so if you want to not have the possibility of special characters.

A rank? 

I would be fun to have a fun chess game on site, where people could play, but there are already tons of virtual chess websites that are built amazingly. Chess.com for example is great for professionals and beginners, as you will be put up against people that are the same skill level as yourself.

Forum wise, you could make a usermade club, where you RP about chess.

What you are talking about is subscriptions, which VIP already kind of is

in my experience with these sites and when something like this was attempted, then people didn't use these forum. I wish that they did, but unfortunately, they don't.

The house club has a list of all members of the house and a number of those members. There is also the user list, where you can set search parameters.

On EU the HM makes both a sorting post and a first meal topic in the Great Hall for new users. So I suggest going to your MoM and HM to ask them to make one at the start of each year.

The sites and their structure began in 2016, and ofc built before then , which was a time before the big boom in trans acknowledgement became a thing. I completely agree that there should be something there to indicate non binary gender identities. However, I don't think the creators of the site had any ill intend, but mostly just didn't have the knowledge about the community back when the site was created. There might be ways to add the option, but it will be thrown on the MoMs of the sites to help the users that already had users on the site with this change.

Not all MoM/HM are going to do that. Just because sites do stuff differently.