I do usually tell the missile troops to engage the general unless there is a better target. You should do this because you might get lucky, unless of course you feel that you should capture or kill him. Then, it's attacking him like you would a horse archer group if you didn't have archers of your own: cavalry attack from all sides.

Number two is obvious, of course. I'm sure everyone keeps him out of the battle unless absolutely necessarry (and it sometimes is).