TH wrote:

What would be the best (freeware-) software to restore/download userdefined
waypoints (aviationbased) from Garmin 196.

For just filing and restoring waypoints, routes, and/or tracklogs, I'd
recommend the freeware G7toWIN:
http://www.gpsinformation.org/ronh/

To see where those waypoints are on topo maps or aerial photo views in
the US, I'd recommend USAPhotoMaps:
http://jdmcox.com
Example:
http://home.comcast.net/~prathman/Screen02.jpg

Do I have to buy MapSource?

No, the main function of MapSource is for loading maps to your GPS
although it will handle waypoints/routes/trackpoints as well.

Is
MapSource roadbased only?

No, there are topo maps and marine charts as well as roadmaps.