[Luce]

I wouldn't put the sense wires on the buss. If there's a little voltage drop between the buss and battery, the alternator will sense it and compensate, and dry out your battery with excess voltage. This will also make your alternator work itself to death in the process. If you have meaty #2 or better from the starter to the battery, you can get away with sensing there.

A buzzer should be fine as long as it's less than 1/2 amp or so, but it will buzz every time you turn on the ignition until the engine is running. A light bulb under the dash somewhere (you don't need to see it)(maybe zip tied to the column) or a resister may be easier on your nerves.