Performing actions on a specific server with BungeeCord

The plugin I am creating with BungeeCord has some features which can't be done with the BungeeCord API. For example, world creation. For this, I imagine I would use the plugin messaging system and have a Bukkit plugin which actually performs the actions. Am I right in saying this?

I would also like to know whether commands in a BungeeCord plugin work for all connected servers. So if my BungeeCord plugin added the command '/hello' then it would work on any server connected to the proxy server....

Performing actions on a specific server with BungeeCord