The best site to learn about Garmin GPS tracking is the Garmin web page: http://www8.garmin.com/aboutGPS/ Also there are free training videos in the Garmin Learning Center: http://www8.garmin.com/learningcenter/training/index.html
http://www8.garmin.com/cartography/mapSource/topo.jsp This Web site explains the garmin mapsouce topo.
The web page http://www8.nau.edu/cvm/latlongdist.html at Northern Arizona University can make that calculation for you.
I did not find any information pertaining to the Garmin Nuvi. However you can find newer updated GPS on this website : http://www8.garmin.com/dealers/
You can download software updates for your GPS from the manufacturer that makes your GPS. For instance, for a Garmin GPS, you can download updates from http://www8.garmin.com/support/download.jsp.
You can read reviews about the garmin automotive gps lines on the following site: http://www8.garmin.com/aboutGPS/. It is a fantastic product.
The Bluechart Garmin is compatible in The Americas, The Atlantic, and the Pacific. This GPS comes with electronics charts. More information can be found here :http://www8.garmin.com/cartography/bluechart/
On their official website, www8.garmin.com/support/download.jsp you can find any garmin updates you are looking for. If that site does not work for you try https://my.garmin.com/maps/updates.htm.
It depends on the area in New York State. You could find the exact tax rate by address in the following web site: http://www8.nystax.gov/STLR/stlrHome
Mapsource ranges from 39.99 to 174.98, it all depends on what you get. Here's the link that gives full details and pricing. http://www8.garmin.com/cartography/mapSource/MGEuro.jsp
NO, you do not need to buy Garmin GPS software if you use a Garmin navigational device. You can just download them at www8.garmin.com/support/download.jsp
No more than 2.2 gigabytes. Depending on the version of the USB. https://www8.garmin.com/support/agree.jsp?id=591 or go to their website. The provided link is right here.