I can't help you much with the CB installation query - there's not much call for those things here in UK nowadays. However, I'd imagine that you could overcome the alternator noise with some hum loop isolation circuitry. I guess a trip to Radio Shack might provide the answer.
As for installing the Zumo, you'll find a dedicated GPS power supply socket, attached to a flying lead which is tied and/or taped up somewhere around the rear of the oil cooler. I needs a BMW lead to mate with your Zumo. If you can't source the required lead, some BMW dealerships can be persuaded to supply you with the required plug to enable you to make up your own lead, although it's not listed as a retail part.
"A map is not the territory it represents, but if correct, it has a similar structure to the territory, which accounts for its usefulness".