I can answer your question about bluetooth GPS recievers. I bought a Garmin unit through Anywhere Map for use with their software. It has a battery life of about 12 hours. It can be velcro'ed to just about anywhere, and for better or worse, it has a powerful magnet inside the case to stick anywhere you need to (There is a thread on Anywhere Map's website regarding removing the magnet, as it can affect your mag compass if it is too close) Having said that, it worked well on the dash of my C-172, on the dash of my Airbus A-300, and I velcroed it to the aft area of my RV-8 cockpit under the canopy. It can be set up to run on ship's power with the included cigarette lighter adapter.
One of the most intriguing locations I've ever seen to mount a GPS reciever, was under the fiberglas engine cowling on a friend's RV-7. You did not even know it was there. That would not work for this unit unless you hard-wired it to ship's power, as you would have to turn on the unit manually. This unit when on internal battery power, must be manually turned on and off. When you plug it in to charge, it turns on automatically. Check out Anywhere Map's website for current pricing. Bill Zorc Vero Beach, FL