Town, nation and global chat all arrive in one feed. You never have to switch channel to read a message. You always see all three. Switching only changes where your next message goes, and the prompt tells you which channel that is.
/tc, /nc and /g switch channel. None of them takes a message. /chat town, /chat nation and /chat global do the same thing.
Global chat is linked to Discord both ways. Town and nation chat are not.
The web map
Your town and nation claims are drawn on the live web map. Open it under Map at the top of this page. It opens next to the site instead of replacing it.
/townflag sets what your town is for. That is the first thing anybody looking at the map wants to know.
Cosmetics
Coloured names, map outline colours and showing your gear in chat are supporter perks. None of them changes anything in the world. Nothing you can buy gives you an advantage, and that includes information, so some commands that tell you useful things are staff only.