No you cannot change your group name once you create it.
Your name is gmod is the same as your steam name. By changing your steam name, you change your name in steam related games. However, bans are not name-specific. They are tied to the steam account, not necessarily the steam name.
You cant
You cant
no, you cant but you can make another account for if you want to change your name
if you have steam wich you need it you go to settings and chsnage your name
u cant
You cant
you cant
You can change your username in settings.
u cant
you cant sry