'Cos I'm a super kind Hippy I'll add my 3 1/2p's worth..............
a) IMHO the north is nicer than the south (slightly lees developed and more areas off the beaten track)
b) You'll get nowhere fast as all roads are very twisty and slow (in a good way) ~ allow plenty of time to get anywhere
c) Assuming our intrepid traveller is on an 'adventure bike' then Corsica has more tracks than you can shake a stick at and was made for such bikes. You won't need a map to find them, they are everywhere. Some are private and some are public but it matters not one jot as everybody uses them, that's how it works there. Just make sure you close gates etc and you'll have no probs.
Have a look
HERE for my take on the place.
Oh and Chas, leave our Wappers alone, he's a National Treasure he is
Andres