Quattro Coupe questions

[agaidos@firepower.com]

Hello
 I went through some of the archives in an attempt further educate myself about the Quattro Coupe before I  
lay down $9300 for the one I found. Unfortunatly the archives gave me more concerns then comfort.
First the car is #347, Mars Red with 77,000 miles
Here is my short list of concerns:
1. Rust-On the sideskirts there is a seam and both these seams have   

   rust. It is more then superficial but small (2inch by 1/2 inch). If its just on the    

   seam it is no prblem but if it started from behind the skirt it 

   maybe way worse.

2. Locking differencial-how often does this fail and and how hard is   

   it to trace out the failed vacuum lines for it.

3. Cracking cylinder head- Is this a real common problem or something  

   that pops up once in awhile?

4. The hot starting problem- My Audi Mechanic thinks this is a   

   booster relay problem> Oddly enough he fixes it with a late model   

   Ford relay with success. However, in the archives one guy 

   (Dave Lawson)goes on about injector O rings, sensors for the  

    injecter cooling fan circuit etc.
   What is the story with this?

Thanks in advance for all the questions. I just want to make the best decision possible when buying this car.  
This has been my dream car for ten years and now I can afford to buy one, park it and begin to fix it up.
Thanks again
Anton