A3 2006 QUESTIONS

I have just bought an Audi A3, 2006 hatcback with 1.6 engine. Hoping that, I would learn many thing from you and have several questions here.   

* Comfort Control Module (CCM) is broken according to the electrician and, the CCM needs to be replaced. What are the differences between the letters (C, J, K, etc...) at the and of the number on the CCM like in 8P0959433C? Can I buy an install any of the CCM from any A3, 2006?

* Could a cruise control retrofit be possible? If yes, would a single stalk with cruise buttons be enough or, should I buy complete a retrofit kit including both signal stalk and a cruise stalk in one kit?

* A warning always says "headlight and rain sensor defective". What is this and how can I solve that? Should I buy a new mirror with a rain sensor and a headlight sensor?

* My Audi's wiper stalk has timer on it. As far as I know, a timer should not be in a stalk that controls the auto wipers???

* How can I get the owner's manual and workshop manual? Is there any link other than buying from Ebay?

Any help would be greatly appreciated...Thank you...