Regarding the air con "click, click"... I read on a Skyline site/forum somewhere that it is simply a worn nylon air box gear. (At least that's what my air con "click, click" is). Yes, it would be expensive to pay someone to fix it, they'd have to dismantle the entire dash.
But, I also heard that the air box is common to a standard Aussie Nissan, with the part available for about $20.00 from Nissan themselves.... I just can't remember the part no!
So if anyone knows it, I'd love to know - I'll pull my dash apart myself to fix the problem!