Chris
No one so far has any luck with getting a phone to work on a JDM model. The connector is different on JDM and it seems incredibly hard to get info on what phones/adaptors work with it.
Sat Nav, yes your right, it's basically junk unless you wanna pay a lot of many to get it converted. One company can do it but your looking in the region of £900. They can also properly convert the radio do you don't need a frequency shifter for £150 -£200.
Badges can be removed and 350z ones purchased easily. Front number plate bracket can be swapped for a Uk one. Only way to change the rear numberplate is to buy a UK bumper. Some go through on ebay.
some differences listed here http://www.350z-uk.com/forum/viewtopic.php?t=1781