Yes, I have thought about it. I know a guy who attached a fog horn to his bike to be heard when he needed to be heard.
1) Yes, I agree.
2) It would appear to be beyond my comfort level. I would ask Brammo tech support for their advice before trying to do this on my own. I would assume that there may be some particular obstacle because I am not sure how the horn draws electricity on the Enertia.
If another Enertia owner could list out the exact step-by-step instructions for the modification, I might give it a shot.