You can chat with your teammates by pressingand view their location by pressing . Like in PvP, you will die when colliding with another player, running into one of their towers or getting hit by their bullet, but not if the other player is your teammate.
To win, you need to control 80% of the map or more, which will stop your enemies from spawning. After that, you have to kill every remaining player without having the territory percentage fall below 80. If you die, you will keep half your XP (when respawning), but every tower in a radius depending on your level around your death place will be removed.