When you say the waypoints, routes, etc. are uploadable and downloadable, I assume that's what they mean when they say GPS compatible and that it does mean the map information can be uploaded from these programs. Am I right?
What who means when they say GPS compatible? If these are claims made by the third party software makers then yes that's probably what they mean. Again the only off the shelf mapping that can be uploaded to a recreational grade GPS receiver is produced by the maker of that receiver. High end mapping grade or GIS receivers may be different.