Getting gold in the coffee breaks doesn't affect the number of golds that show up in your game status, and doesn't affect getting all gold tests for a license (the coffee breaks are not tests), and doesn't affect getting the all gold prize car.
As for 100%, it gives you a black F1 car. A little disappointing seeing as the F1 car can also be won elsewhere (Nurburgring 24 hours). If you can't get all gold licenses you could aim for 100% completion, but frankly if you have the time to get 100% completion, you have more than enough time to practise and easily gold the licenses. 100% completion is easier than getting gold licenses in driving terms, but it takes a lot longer!
As for 100%, it gives you a black F1 car. A little disappointing seeing as the F1 car can also be won elsewhere (Nurburgring 24 hours). If you can't get all gold licenses you could aim for 100% completion, but frankly if you have the time to get 100% completion, you have more than enough time to practise and easily gold the licenses. 100% completion is easier than getting gold licenses in driving terms, but it takes a lot longer!