Never heard of anyone doing this before, it would be a way cool mod if you can pull it off. I dont see any reason why the airbag shouldn't just be plug n play but dont take my word of it. Could you not 'borrow' the wheel to see if it fits before buying it?
As far as controlling your headunit it depends what model you have. Sony do make interfaces for their newer headunits
http://www.caraudiodirect.co.uk/prod...4837902214ad89