hi, think i have some answers for you....
if you are using the android sdk 1.0 or earlier you can get directions etc, here is an excellent tutorial...
Google Driving Directions - MapView overlayed :: anddev.org - Android Development Community | Android Tutorials
if you are using a later version then the google.DrivingDirections library is no longer available so the above tutorial wont work, you can use kml files to load a route though, here is a tutorial to do that...
???: Android - Driving Direction (Route Path)
Hope this helps!! I'm using a later version so ive done the kml tutorial, let me know if you need any code/help as the tutorial is a bit confusing! the first tutorial i have but cant run as using a later version but you can download the source code from the site, the app is on the marketplace too for free (called AndNav) and works a treat!
Iain