You can break a banner with any tool or without any tool as well. The hardness of Banner is just 1, and it can be quickly broken with the help of an axe.
Build them by combining a normal minecart with a furnace. These can be set in motion by loading with fuel (right click whilst holding the fuel, eg. coal) and.
There is no command to change a player's name. As a workaround, you could fake it by hiding the player's name whilst teleporting a named entity onto them.