How do I change my username, and if I do change, can someone take my username that I currently have? Thanks!

Heres how usernames work to change your name go to settings on the hoem back and click that edit liekvthing beside your name the cost of changing it is 250 bucks.
and no nobody can take the name because It will say that name is already in use

https://www.brick-hill.com/settings/

Username > 📝 > "New Username"

^^^
It costs 250 bucks, make sure your prepared .
Also no one can take your old name, dw.