audio S3 stereo in my A3?

[JordA3-8p]

Hi guys wondering if you can help me out!

I want to put a touchscreen with nav in my A3 but id preferably like to keep audi parts. Not aftermarket.

I have a 2007 (56) A3 8p 2.0tfsi Sport Quattro with the standard headunit and no steering wheel controls. 

Can I fit the touchscreen headunit out of a S3 8p in mine easily? Would it work better if i change my steering wheel also so it has the steering wheel controls?

Thanks in advance!