For those who have not been studying trip planning software, MapSource is still current. It heads the list at http://www.garmin.com/us/maps/trip_planning_software
. BaseCamp is newer, and Garmin has added many new features to it: 3D terrain views, satellite images, and geo-tagged photos. They both manage maps, tracks, routes, and waypoints; and transfer them to the receiver.
[opinion] MapSource runs faster on my computer. Its user interface is, to be generous, clunky, but once learned, it is fast and manages the data without the new features getting in the way. [/opinion]
Responding to your numbered questions:
1. Most GPS models in the Garmin outdoor line can navigate from a collection of waypoints, typically up to 30 - 50 waypoints. You can get the waypoints in the ACA files, make your own on your computer, or find them on the Internet. You load them into the GPSR with any of the Garmin programs or many more third-party programs. You can even create them in the GPSR itself, although the small screen and limited keypad make this tedious.
Note that all you transfer are the waypoints. When placed in sequence, they define a route. If you have an auto-routing map product, City Navigator for example, in your computer, it will create straight-line navigation directions or road-following navigation directions along that route, as you choose in Preferences.
The most basic GPSRs create straight-line navigation directions only. Auto-routing GPSRs, when loaded with an auto-routing map product like City Navigator and the same sequence of waypoints, will also create straight-line navigation directions or road-following navigation directions along that route, as you choose in a screen under the Routes menu. You can recalculate at any time.
Care is needed when planning an auto-routed trip on the computer. The GPSR may compute different road-following navigation directions than the computer did, even when loaded with the same map. Occasionally, I need to add a waypoint to direct the algorithm to the road I want.https://buy.garmin.com/shop/shop.do?cID=145
lists the most popular auto-routing models for biking. The "sport" models specialized for golf, swimming, biking, etc. appear not to handle routes with several waypoints.
2. My current receiver is a GPSMAP 60Cs.
3. My receiver and the other "outdoor" units name the two kinds of navigation directions the same: "off road" for straight lines and "follow road." The difference is that they can handle 30 - 50 intermediate waypoints, where (if I understand correctly) the Edge navigates to a single waypoint at the destination. Correct me if I have that wrong, please.
If I want to switch to the other kind of navigation while following an existing loaded route, I press MENU > RECALCULATE, and select Off Road or Follow Road.