Welcome Stu ~ most has been covered above and also in the buyers guide that you've been reading.
If you can try to ascertain what fuel has been used that's useful info as the Zed should have only been run on Super Unleaded and lower Ron unleaded fuel can cause damage to the engine especially if used for long periods.
Check to see if the boot opens with one press of the button, if it takes two presses to clear the latch it's not a big deal but just another bargaining chip for a cheaper price. To fix that it will likely need either new boot assist popper springs or the "penny trick" doing to it to fix it.
If the boot doesn't hold it's own weight up & wants to drop then that'll be the gas struts going or gone ~ again easy fix (new struts) & another bargaining chip.
Service schedule for the 350Z here which is useful for checking what should have been done depending on the year/mileage of the car; http://www.350z-uk.com/topic/31110-service-schedule-for-a-350z/
Enjoy the test drive.