So I have had reply from Ludei about the above.
Leaderboards and achievements are using the social platform services and not Ludei's.
The share function is just a general device share function. So lets say you had a link you could share it to chrome. So nothing to do with the social stuff.
There are no wall post functions at the moment. That said it could work in combination with the official C2 Facebook object. That would need testing when I get chance though.