Wochenkarte in Salzburg

No (nice try). The Wochenkarte is valid for transportation for one week in the "Kernzone" (core zone) of Salzburg. You can get to Berchtesgaden either by bus or by rail. The Watzmann Express bus (RVO 840) goes more directly to Berchtesgaden and is thus faster (a little over 50 min). It leaves from the Hbf, not from the bus slips directly in front, but from a bus stop on the street beyond them, to the right looking out. A one way ticket is €4,90/adult. For a round trip, buy an RVO Tagesticket from the driver for €9,50/adult. That is valid for unlimited use for the day and will cover the round trip plus use of all the other buses in Berchtesgaden (except the special mountain buses from Obersalzberg to the Eagles Nest). The train takes a little over an hour through Freilassing (possible change of trains there). You can do it with a Bayern-Ticket - €21 for one, €29 for up to five people. The Bayern-Ticket will also cover all the buses in Berchtesgaden like the Tagesticket. One point to note, the Watzmann Express makes it's last run back to Salzburg around 6 PM, so if you want to stay later, use the rail option.

Thanks, Lee. I couldn't tell from their website if it could be or not. I am going to follow the Rick Steves plan and take the 840 (the Mirabellplatz stop around 11:18 works best for me) to Berchtesgaden for the Eagles Nest Historical Tour and return as RS suggests on the 18:15 bus. Should I assume that the people who run that tour will get us back on time to catch that bus or should I confirm that beforehand?

Here is the schedule for the Watzmann Express. You'll see it also leaves Mirabellplatz at 9:18, 10:18, and 12:18, although the 12:18 bus gets into Berchtesgaden Hbf at 13:01, so that would probably be too tight. Plus the 12:18 only runs on school holidays. I assume you are talking about the Eagles Nest Historical Tour. The website says the tour leaves the Tourist Center at 1:15 pm and takes about 4 hours, so you should get back with plenty of time to catch the bus. Of course, you will not have eaten since before 11:00, so you might be pretty hungry by the time you get back to Salzburg. In your case, I might suggest you use a Bayern-Ticket and take the train. That way you could have dinner in Berchtesgaden before you return. If you have questions, you can email David at harper@eagles-nest-tours.com. I've been in email contact with him recently, and I believe he is a native English speaker (at least his English is very good).