Jamie,
Your experience is very similar to my own and several others on here. My car also came with no spare key, but the importer eventually managed to get a key from Nissan UK and paid for it to be cloned/coded at a Nissan dealer.
My car also had no service history, but I saw the history for another car imported at the same time, and it was totally indecipherable anyway. I had the car checked and made sure I got the BIMTA certificate. The overall condition of the car was so good that I was confident that the mileage was accurate. That was in March '06 and so far no reason to be concerned (touch wood!).
Sorry can't help with the Sat-Nav, as mine did not have that option (though the previous owner had replaced the standard radio with an expensive after-market unit by Clarion, which includes a double din screen).
Jim