Well, it depends. The sensor bracket is bolted to the back of the block and then the bell housing is put on after the sensor depth is set using a feeler gauge off of the reluctor ring on the flywheel…. are you supposed to remove everything to get at the bracket? Yes…. Do you have to?… Depends…
If it was removed when the clutch was done, and if the hardware is not seized, and if the bracket is not seized to the split dowel on the back of the block (aluminum on a spring steel dowel so it often corrodes), then you are lucky and can change it with the engine and transmission in the car. However if you are unlucky, then everything has to come out to get access to the bracket so it can be changed. If some of that epoxy got into the allen head bolts that hold it on the block, it will all have to come out. The amount of space to work back there is literally inches. Sometimes lowering the engine and front crossmember a few inches with everything still connected allows for enough room to work on it and get it apart. Resetting sensor height after the fact can be done with shims used as a 0.8mm depth spacer temporarily glued to the bottom of the sensor. Once height of the bracket is adjusted, this must then be removed.
Any decent Porsche shop will know how to do this work. Just eluding to what you may be facing. Good luck!
BTW, none of this has anything to do with your fans or temperature gauge. That problem is because you also have a poor ground at the end of your engine block (right near that sensor bracket). It is the smaller brown wire. You also more than likely have an air lock. Turn the heater to full HEAT while car idles and bleed at the bleeder fitting at the top front of the cylinder head with the radiator cap OFF. When all the air is out of the system, your fluid level will no longer change with the cap off. This you can do yourself since the shop did not do it for you. And while at it, ensure that you have the PROPER coolant in your car! It should be Phosphate and Silicate free. If it is green, it is the WRONG coolant!