. The terms of use are more liberal than using Google Map Tiles.
The following Java example might give you some insight regarding using Google Map Tiles:
If you find a solution, please post.
Now, the Navigation part. I think you can only use Google's Navigation API if the user is connected to the Internet.
Here is a very simple way to navigate from your device's location to coordinates you specify. It uses ActivityStarter and while not exactly what you are looking for,
it might be useful

The start location is the location provided by your Android Location Services, the destination is the coordinates provided as shown above.
Regards,
Steve