find yourself a good healbot mod. most of those mods if you set them up correctly you can make it so one button can control different heals in different situations. ie: cast greater heal when your tank is at a cetain %. and flash heal at a different %. Bind that that to a key you can spam easily while focusing on your tanking. i can't really say what heroic boss is the easiest with your setup O_o but depending on your gear and monuverabilty with controling those classes i think you could down most heoic bosses ;p.