Q1 - I find the price comes down once they cotten on to the fact that you know what you are talking about...
e.g. Midas wanted to charge me 230 to flush the radiator in the missus XR6, as soon as I said I wouldn't pay them for something you can do with a bottle of coolant and a garden hose; the other 5 things that were on the list as "urgently need doing" suddenly didnt need doing any more
Q2 the clunk may have been related to the rear gearbox mount, to change the clutch you drop (move) the box so they would have had to of done it up to correct spec, possibly eliminating the "clunk".
