I love Slam Dunk too mate, but I have some bad news for you, at least for now.
As for now head shape editing for NBA 2k12 is still not possible, but word is that a head shape editor is in the works. Hopefully soon in the future we'll get some Slam Dunk cyberfaces coming, but that would most likely be from those wicked talented Chinese patchers at baballs.com. Most people in here aren't that crazy about Slam Dunk / don't know about that basketball manga masterpiece.
For your questions about SD mods for NBA 2k11:
-Every single team in the manga, even some teams that weren't shown in action in the manga (dunno about the anime, though). The whole thing would be a very large download, but we can choose which teams to download separately. Pretty much all players per team are available.
-Not sure, but I think NBA player ratings. This didn't matter anyways since you could edit the ratings in-game or use Vlad's Reditor.
Hope this helps. Keep your fingers crossed for a 2k12 SD mod!