Paris, France to Freiburg, Germany...by rail...length of trip?

Jan, I kindly suggest you learn to use the bahn.de website to figure this out, rather than counting on people here to do it for you. It is actually faster, and you will feel empowered. You will need to do that anyway for your trip from Obertraun to Venice, to understand all the options.

Jan, You'll be leaving from Gare de L'Est in Paris for Freiburg im Breisgau Hbf...count on ca. 4.5 hrs. If you have a Eurail Pass which includes Germany and France, it's valid, since Basel is included as part of the Ger. section. You'll need to transfer in Basel. Both legs are by speed trains. Unless you intend to do some additional long rides, ie., Munich or Berlin to Paris or Freiburg-Berlin, Munich-Berlin, etc., you might want to consider getting a point to point ticket. Some like to break up the ride; if you're not adverse to a 5-6 hour ride, and then transfering, you may make the Pass work in your favour. I like looking at the lovely French and German countryside on long rides from ICE trains.