Android App Development

I just spent 1.5 hours getting an Google Maps fragment working in a test app. It seems like a kind of difficult API to get things done with.

I want to make an app where users can plot and upload street routes to a server, and then the app will time how long it takes you to complete the route, basically a street racing leaderboard app.

Does anyone know how difficult it would be to do this?
Keeping the GPS based times accurate to the second might be difficult.

>>3
If the routes are set, and the street racers are set to take a specific set of roads, then project the gps location to the nearest valid road and rank by least remaining distance to the finish line.

It's a bit more complicated if the racers can choose other routes, like a race through a series of check points. In that case ranking first by the number of check points completed, followed by length of the shortest path to the current check point. Shortest paths to each check point can be calculated offline, once before the race begins, using single source shortest path.