I can't get the upgrade to download, but I will verify:

1) The N810 comes with the car mount bracket piece, and you can swap it out with the N800 bracket that came with the navicore kit. If you don't have the old kit, you just need to buy the car arm piece direct from nokia.

2) Your navicore key WILL activate the N810 map"oftware (It's in their FAQ) but you need the new firmware

Hope that helps!