1. Probably, but it would depend on the profile of the tyre you are using.
2. Check the type of exhaust rubbers you are using. These Golfs use a specific type that both hold the exhaust very tight to the body but prevent the exhaust from banging on the bottom of the car. If you have the big 'O' ring type, then that is probably your problem.
3. Handbrake cable adjustment is not difficult, its just a little time consuming to get it right. Follow the haynes to the letter and you will not find any problems. The adjustment is done inside the car, but you need to jack up the rear of the car to be able to turn the road wheels.
4. You do not need to re-torque the head. If you do, you may snap the bolt as these bolts are 'use once' stretch bolts. IE, they stretch when torqued by design and therefore should not be used again. The final torque is a quarter turn after set torque anyway, so in effect, there is no final torque.
5. Google it!!

6. These are high compression engines anyway and you should be using 98RON fuel because of this. if the engine is set up properly, then I do not see any reason why the engine life should be shortened significantly. But an engine can last twenty years or twenty minutes, depending on how the engine is used or abused.
Because of the amount of material removed from the head, you may need to buy a vernier cam pulley to readjust the cam shaft timing more accurately. The rolling road should be able to advise you more on this subject.