You can leave your charger plugged into the car dock and once you dock your phone in it the phone will recognize that it is in and open up a new menu that gives you the option to start navigation along with other things... There is a good app called car home ultimate that you can have open instead and it tells you your speed and direction as well even when you aren't in navigation yet
This sounds like an app I have been looking for. Can't find it on the store though. Could you double check the name?
BTW, doing 246 as I type here!