I believe the Aus spec ones should fit straight on.
N13 Reebok seats fit as well on the Aus spec, so it should be the same on HR31
Later model seats don't bolt on, you will have to modify or make rails.
No idea on how much gas, the machine does it automatically I believe. Cheers for the aircon diag, I remember reading it in the manual, will do it once I get some time. Does your other compressor have that brass screw thing?
Totally off topic, but the Indian dude at the shop (where you initially parked) was me LOL. I was getting the air con regassed on my car (I didn't know Carbon did regassing). The compressor on my car doesn't engage, so have to find the electrical fault.
Maybe replace the compressor again? fatz has a couple lying around...
Chances are, a clean stock AUDM S15 will be better condition than a JDM one of equivalent mileage (not that imports have very high chance of being wound back). The AUDM ones (the standard ones) are usually owned by people who can afford to service it properly and the km are most likely genuine. Plus you get a 260 km/h speedo .
If the car you're looking at is modded then it gets tricky.
D2R, you can get them from powerbulb (genuine)
http://www.powerbulbs.com/au/store/category/car-bulbs/fitting/d2r
Or you can pick up eBay ones for less. You get what you pay for (been there done that with D2S).