This video is as good as any (2010 A3 Cabriolet). Seems the window motor is behind plastic trim which uses a mastic to seal. That’s likely to be the hardest part. Other tools will be deep socket or Torx for any screws, 10mm hex socket, etc. Electrical connections can be a pain too. Invest in a head torch, and a couple of small screwdrivers for these connections. Regards the motor, normally daft money from Audi. Probably made by Valeo anyway, and suffer water ingress. Either the physical connection or the motor, so check these when stripping out. Take the part number and source from EBay. I assume the motors may be similar to the fronts? You can double check on LLL Parts. I wouldn’t have thought it was fuses if other windows work, but hey, check anyway.