Driving Profile Shaping

You might check to see what map is selected. If the "Global Map" is selected, that is not a routeable map. Some maps are routeable, some are not. That one is not. It is just a basis upon which to draw map features. The map from the device would be preferred and that should help you route.

Also some maps will route some kinds of activities, and some will not. It depends on the map. What map is installed on that device?

Let me edit this because I didn't answer all the questions:

Your route can have preferences, and the walking activity can have preferences. These can help with thinks like avoiding certain map features, or places, etc. That can have an impact on efficiency. In a driving route for example, the most efficient route might take me through a toll road, but if you avoid tolls, you might get a longer route.

Tracks and routes are similar. Routes represent calculated, tracks are actual. Another, VERY simple way of explaining is routes are where you are going, tracks are where you have been (I know some users disagree with that but it is one way of looking at it). Tracks can also be drawn and can be followed, so they can represent where you are going as well. It depends on your use. But mainly calculated vs actual.

The Google Earth features are there for allowing people to work between the two. Some people like BaseCamp for helping with their device, but want their data on a more global service such as Google Earth. There are other uses for it too but I am personally not a big user of the Google Earth features. I'll let some of our users talk about that.

Does that help at all? Do you have more questions? I can walk you through finding some of the features if you need.

That pretty much cracks it. I use GE to view my routes/tracks prior to hiking them. It shows me how accurate my map is. If the route doesn't match what I see in GE I can adjust it in Basecamp until it does.

Some people also like to collect tracks for historical data and reference. Fitness users like them for various performance metrics. There are many other uses as well. And there are some that don't have much of a need for them at all. It depends on your device, and your use of that device, and what data you care about personally.

........
Please help me with the following: etc.

This may also be a great help with your learning curve:http://garminbasecamp.wikispaces.com/

I am using the U.S. 100K Map that came with the device and default preferences, but still no luck in routing along roads.

That's because the 100K map isn't routeable.

I guess the next logical questions are:
What maps are routeable?
How does one know a map's limitations?

Crikey, I don't think any of us have time to list which maps are routeable. You can normally find out from the map supplier. The US topo 24K maps are routeable though if that's any help.