gearbox cost + other questions.

How much would it cost to have a gearbox replaced on a 99 freelander 1.8? I have seen units on ebay for around £150 but would like to know the rough labour time.
Locking wheen nuts - 2 have been removed from the car but the rear 2 are in a bit of a state where someone has tried to hack them off. can i just go to LR and they wil sell me one - Hopefully i can get the nut off oherwise i a bit buggard as the rear tyres need replacing.
The car has a roof rack but the keys to unlock it have been misplaced. The number on the lock is 66 - are replacements available?

5-6hrs to replace box. multiply that by charging rate. i charge £20 ph by the way

where are you based?

lancs