Hi Simon, firstly congrats on the great purchase!
I can't help you on the Volvo side of things, but I also have a Japanese import car - a LandRover Discovery V8.
I can confirm that the Japanese really look after their cars - their equivalent of the MoT test for older cars is very stringent and expensive, so the cars that have lasted this long are exceptional. One thing you will have to be aware of though, is that the Japanese heat wreaks havoc with some plastics and rubbers.
You'll probably find any window rubbers will have perished and will leave nasty streaks down the paintwork when you wash the car; any convoluted plastic tubing over the wiring under the bonnet will be dust like - it'll literally crumble to nothing when you touch it; and the tyres will be Japanese spec, which are very hard compared to ours - they're not very good in the wet, lets just leave it at that
You'll also probably find all kinds of electronic goodies have been installed in the car - the Japanese love their gadgets! If you're lucky, it'll just be toll road transceivers, otherwise you could have a whole load of in car entertainment fitted - but as our radio frequencies are different, most of it won't work. I had a fabulous radio/DVD/TV setup in my Discovery, along with some whacky quad roof aerials, but non of it was compatible with UK services, so I've removed it all barring the aerials - which make it look like an unmarked Police car lol.
On the upside of course, it'll be rust free - in fact its condition will astound you, even if you're expecting it to be good
We should learn how to drive in the snow & ice and stop using road salt - our cars would literally last decades longer! (But maybe thats their plan to support the motor industry...?!!!)
Finally, we'll need to see the pics when it lands!