Let lupo 3l – tooth strap change

Hello! In the search function KM got hints, but not really an answer for my question, therefore here my request: my Lupo 3L (year 2002) (today 185.000) KM got a new transmission since there was a transmission damage – everything is running. I brought it today to the inspection/service (in VW contract workshop) and there was of course also said that the timing belt is overdue. Now the following questions: 1. Does not the timing belt necessarily have to be renewed during a transmission change? If yes: on the transmission change calculation at that time it is not mentioned, but then I could save it now. 2. If I have to change the in fact: WELCHEN timing belts from WELCHEM manufacturer should I buy the best in your opinion? 3. If original VW part: which part number does the part or where find out and get those? Thank you in advance !