Hi back; some info
I have done the Euro delivery, and am now back in the US awaiting the Q5 in 45-60 days.
The speedo is easy--just change the setting for the center instrument panel display that shows the speed to kph. The speedo of course will still have the big MPH gauge w/ the little kph numbers, but the digital display will now be in kph. The cruise control settings are then in kph too; handy for all the speed regulated areas, cameras etc. The trip computer stays in miles type calculations, unless you separately tweak that.
Can't help you directly on Nav, but can speculate it's a two step process as you are probably thinking. You need to get to an MMI version that is for Europe, and then you also need the map data. Pricy apparently now that the stuff is on flash instead of on discs, and apparently only dealers can do it now. For Euro delivery Audi just loaned us a Garmin. Not perfect for stuff like easy zooming out like via MMI, but plenty good enough for 98% of the true needs of getting from A to B.