The main website shows this, but the "List of all changes..." link seems to not work?
Anywho, here's a bunch of stuff.
This link describes the custom stats on this server:
Here are all of the custom items on the server to date:
Server events can be found here:
There are special boosts sometimes like "Happy Hours" or "HH" which improve drop rates of items, "Green Names" which greatly increases rare monster spawns, and an extra experience boost sometimes (on top of the base one described in the top image), and a bunch of other things I'm likely forgetting.
I'll edit this to be a little more detailed when I'm not half awake, unless @TheIronSheik posts a academic textbook worth of info about Ultima by then 😚
Edit: Oh and welcome to Ultima!