Do they put fuses in grounds? Do they switch a ground or neutral to your light?

No they don't.

You never switch a ground for safety reasons. If you disconected the ground and leaned up on the positive, it could make your "pace maker's" beat rate go into double time!

A 12 volt battery would not be life threatning (in most cases). Just don't be standing in a puddle of water with your new sneakers while disconnecting the rusted positive terminal with your bare hands.

Dont skimp on price either. Go out and buy an American USA brand, for a little more then 40 greenbacks and you will have a switch that will last a lifetime.

I would not even consider one of these devices for theft reasons. The criminals today can gain access to the most highly sofisticated alarm systems.

I never have used one, but the steering wheel device looks like it would be more then a petty criminal would want to deal with on a Saturday Night!