Edward Eustace

The 2006 Audi A6 3.2L with 170,000 miles on it, was leaking oil i was adding lucas oil leak. A week ago it started roughly backfired and died, it did end up starting. I replaced the plugs and coils, when I did the driver side 3 coils and plugs where covered in oil the passenger side only one coil, the one in the rear was covered in oil. The car did overheat we stopped immedialty and the audi service center replaced both cooling pumps. From what I have researched my next step is to remove the valve cover and replace all the plug gaskets and cover gasket which has signs of leakage in several locations. The only concern is this happened so quickly.
SO as I see it there are several items I think are causing the issue. The oil is not like choclate milk and the coolant levels have not dropped, so I believe I can rule of the Head Gasket
-replace the valve gasket/coil gaskets
-replace the crank shaft half moon while I am in there (how do I do this with out take the entire bumper off???)
-Replace the O2 sensors while I will have easy access to them-IS THAT NEEDED?
-Replace the ECM (Is that needed? how easy is it?)
- Also is there any pump or sensor that regulates pressure in the valve area that could cause this issue?
- When I look at the valve cover there are two sensors on top of the valve cover do they play any role in what is going on?
- I do not have a computer to pull the codes so i do not know if there is a certain cylinder that would have any issues with the associated valves? How can I get a inexpensive one and would it help with any of the above.
- I can do all of the above work on without a problem when it comes to replacing the actual valve gaskets I have no idea no to proceed. I hope that I dont have to go there.

I apologize for the long post but I really need your help with this any suggestions of where to start and how do I identify other issues moving forward.