bit dubious that its the actual lock thats broken - surely its just a catch and a soleniod
it was your rear passenger door that has problems? - for that price i'd want a gurantee that if the problem isn't cured i'd want my money back!
as for your list
1 - tell them to fook off
2 - £50 to rectify with discs and pads and hour of your own time
3 - wishsbones possibly? basically they are £25 per side and just 5 bolts un-does them - about an hour's labour max
4 - get a new bracket welded on
5 - minimum legal limit is 1.8mm so plenty of mileage left
6 - i paid £30 from VW themselves for my fluid change 2 WEEKS AGO!
7 - need them - time to upgrade to full aero
don't worry about the cambelt - its 40K or every 4 years. I expect your service book isn't stamped with it so they've taken one look and gone 'its not been done' they keep trying to tell me the same thing yet i've got receipts to prove the work was done