If you had actually read, there are plenty of threads answering your questions. The search function can find out info on all the questions you have asked. They have all been discussed in detail.
V36 comes in
- Base model - poverty pack...just the car no luxuries.
- P - Premium pack, leather
- S - Sports pack - half leather, paddle shifters (auto), bigger brakes (akebono on the coupes, sports brakes for sedans), (19" on coupes 18" on sedans)
- SP - Sports + Premium
Things to look at....nothing much...pretty much as you will for any other car.
Reasonable mileage...i dont really have an opinion on this one....the lower kms, the more expensive.
I'd import this myself from Japan using Iron Chef or Prestige Motorsports. They are highly respectable and recommended, a lot of the guys on the forum have used their services to secure their pride and joy...other car enthusiast used them...you can go on any import forums and find that they are talked about) . I personally do not like dealers because a lot of these cars sold at dealers have their mileage tampered with (this has been discussed at length...again please read or use search function)
370z dash...again, the whole nav conversion thing has been talked about way too much. Chris from Qld would tell you to get a non-nav non-bose car, he can put a nav system in and you can use the oem screen. Personally the bose system is overrated...
Servicing....Infiniti recommends 6k kms...you can just follow the 370Z service schedules as they have the same engines