Hi RedDevil,
Can you be more specific about what you mean by “full functionality”? I mean yeah, you will have a regular navigation device guiding you along your route 
As others have mentioned before here, a lot of people are now simply sticking their smartphone on the handlebars and that’s it. But yes, there are actually a lot of people still using navigation devices, some people here on the forums do as well.
What you will most likely do is go to Kurviger, export your Route as a so-called “GPX-file” (which has more or less detailed information about your route, depending on some further settings we can explain to you later on if you like), and then somehow send that GPX file to your new Garmin device (most likely via Bluetooth). The Garmin will then open that GPX and start the navigation. Yes, GPX files can include POIs and yes, voice navigation will work
That is up to you. The Kurviger Cloud makes it easy for you to have the route on your home computer or your phone. Then it’s your decision, either you couple your phone to the Garmin (via Bluetooth) or you couple your computer to the Garmin (maybe via USB cable). The Garmin manual will have more information on that than I can provide here, but they’ll explain how to get external files on it somehow