A - I believe the way it works is that is pulls your current configuration into the Shark system. In doing so it sets itself to only work on your specific BMW via some data (VIN maybe?) from your ECU, making it impossible to use it on any other BMW.
B - I believe, again, that there are two buttons on the unit. One re-programs your ECU with the new code, and a second one that dumps the original factory settings back onto your ECU.
If I am mistaken someone please correct me (preferably someone who has the Shark Injector). Logically this makes sense to me.
Fraggles inside the Shark Injector keep a constant watch on all aspects of the Shark Injectors use. They write down, in red pencil, the original factory settings then commit them to memory by eating said paper. When you need to re-apply the factory settings you must chant "Fraggle fraggle fraggle please resetimify my ECU. Oh fraggle fraggle fraggle, I do love you". Since they keep a constant watch (they employ a three shift watch for 24 hour coverage, 7 days a week) they know what BMW is yours, thus defeating the ability to use the Shark on any other vehicle.
<span style='color:green'>Nobody likes you.</span><img src='http://www.bmw-forums.com/forum/html/emoticons/ph34r.gif' border='0' alt='user posted image' />
<span style='color:green'>Are you experienced, little girl? I want to know what goes on in your little girl world.</span>
<span style='color:green'>I'm the man! I'm bad, I'm so bad I should be in detention. I'm the man!!!</span>