2003 audi a6 quattro 3.0l abs, traction control light
 

I sent out the abs control module and was found to have no hardware issues so i took it down to a speciality european shop. he stated that I have a fault with my passenger side rear abs speed sensor and needs replaced.
1st. is this a easy fix if i buy the part, whats the part number so i know i purchased the right one, does it have to match the other 3 speed sensors brand.
2nd. He stated I need to replace my whole catylatic convertor due to a check engine light.
I have an OBD check engine light tool and this is what I got
p0421 Warm up Catalyst efficiency below threshold (bank 1)
p0456 Evaporative emmission system leak detected (very small leak)
Cal ID 8609095596 C15AA

3rd. He stated that I needed to replace my torque convertor in my transmission. Is this true as people I talk to say there is no way for him to diagnosis that without taking off the hoses and doing a pressure check, that his computer wouldnt be able to read a fault on that. Is he taking me for a ride?

Any suggestions about if i can complete these repairs my self as he quoted me 350 for the speed sensor 1250 for the catylatic convertor and 1400 for torque convertor labor and part.

And will this work to replace that sensor

Without VAG-COM, you're just guessing...although the fact that your car is an 03 3.0 does mean that it will need cats and a torque converter at some point.