Knight Rider 206

Bought used 2005 2.7t AR with 92k mi on it.
-Replaced timing belt, water pump, thermostat at 93k,

-One week later CEL light comes on.
VAG-COM reading:
19537- engine temp to low. (Coolant Temp Sensor)
17866- Sensor 1 for EGT, bank 2 ..short circuit to ground
-Audi dealership says they are emission related sensors and not urgent fix

-Drive it 1-2k more with no problems on road trip back home.

- Turn on car on one morning and engine makes loud rough, noise (its not cold outside) Turn the car off and wait 10 minutes, turn back on and engine makes no noise runs like normal.
- I get oil change, full synth Amsoil

-Car runs smoothly for a few more days + 1000mi, gets me home safely.
-Go to turn car on 2 days later and makes same loud, rough noise from engine, except now i have a flashing CEL.

-Didnt drive it at all with flashing CEL, had it towed to a German Auto shop in Seattle, and this is what they sent me:

With regards as to why you brought the car in:
1. Flashing Check engine light & rough running: We are working on diagnosis and getting the coolant temp sensor replaced.

Other items we noticed during our inspection:
dv hose on both banks cracking from on charge tube side 2 recommend hoses
$32 Engine oil is over filled by over 1 quart 5 .3 to fix
$334 d/s dv leaking 3 needs new dv
$910 secondary air pump is loud needs new pump 3
TBD (do at same time as cam plugs)both charge tubes over timing cover guides are missing 4 have to R&R timing covers to replace
$90 missing nine under tray fasteners 3
$106 non german oil filter 4
$250 exhaust clamps leaking and clocked the wrong way 4 recommend install new clamps
$377 trans output shaft seal leaking 4
$400-600 p/s front inner cv boot leaking grease 3 tripod
$2500 front lower cabs torn 3
(INCL) upper cabs cracking font 3
TBD d/s turbo leaking oil internal 2 (Looking at $1397 in labor charges, may want to upgrade turbos)
$72 fuel filter old 3
$1500 cam plugs leaking 4 (includes VCG, CCTG and cam plugs)
(INCL) cctg leaking 2
TBD p/s side valve cover leaking 2 do cams plugs first, clean area and monitor
$1060 power steering pump leaking 2, needs pump
$445+ oil leaking into valley pan area recommend starting with all breather hoses and recheck 4

codes
engine
$53 to diagnose 17866 exh gas temp sensor to start
$53 to diagnose 19537 engine temp to low to start
$53 to diagnose 19497 power train data buss missing temp to low same to start
$53 to diagnose 18058 power train data instruments to start
$105 to diagnose 16684 miss random to start
(INCL) 16688 miss 4
(INCL) 16685 miss 1
(INCL) 16686 miss 2
havc
$53 to diagnose 01592 air sensor
instruments
$53 to diagnose 01309 same
level control
$53 to diagnose 01772 signal from temp

I had it checked by mechanics before buying it and they mentioned none of these problems. I didn't have any problems with the car until i got my timing belt etc replaced at an Audi dealership. Could any of thee issues be related to their work on my timing belt, water pump etc? It seems like the flashing CEL is most like related to the EGT and coolant temp sensors flooding my cats. What should i do? Any help much appreciated.