Folding mirrors retrofit you need the followng:
-power folding units
-new door modules
-new trim if you want the official look
- new thumb adjustable switch that has the folding mirror positon
-Ross tech or OBDeleven cable to recode the car
This retrofit is very doable!
If you're looking at lane change assist then get your wallet out:
-wing mirrors with side assist lights
-'A' pillar trim and switch for modes
-two radars to be installed underneath the rear bumper also needs to be calibrated
- if you have the S line model then you also have audi sense so might get away from having to purchase the front camera and modules involved.
In fact I wouldn't even try it if this is new to you, the parts list is unbelievably huge. It will depend on your level of DIY and if you're unsure you'll easily ruin your cars electronics and control modules. Get a specialist audi retrofitted to do the job if you're willing to shell out.