transit requests directions via public transit routes (where available).
About the "I would also like to get traffic information such as busy routes, congestion, etc." I have not looked into this, but my code should get you started pretty good.
Found this in the google directions api:
"For Driving Directions: Maps for Business customers can specify the departure_time to receive trip duration considering current traffic conditions. The departure_time must be set to within a few minutes of the current time."
Yes. You would have to code all the functionality yourself. AFAIK there is no library that does that and of course Google Maps Android API v2 doesn't (and most probably won't) provide such functionality because it is too specific. I still think this would make a pretty useful library.
And can we extract the points to compare them with the ideal answer which was to be traced?
Yes. That would be simple after you are done with everything else.