Why when even using Click & Fight system or group attacks do i have to continually order the Avatar to attack? Is there a way to overcome this? The heroes seem to have no problem attacking

No... Unlike the heroes, the avatar doesn't have IA. He attacks only the enemies near him, so the best way is to use it like a "tank".

Since you get negative effects when your avatar dies they made it this way so he won't accidently get pulled into a huge group of enemies and just die while you are not looking.