Hello Lalaland and welcome to this forum! As for your questions:
1) Yes, the train ride from Zurich to Interlaken via Lucerne is beautiful, but as it isn't the quickest route the timetable may indeed not come up with this. If you enter your trip in
this timetable, you can select 'advanced search' through the blue link at the bottom of the search fields. This allows you to enter several 'via-stations'. If you fill out Lucerne and Meiringen as your via-stations, the timetable will show connections through the scenic route over the Brünig Pass.
http://www.zuerich.com/en/welcome.cfm2) After such a long train trip it's wise not to plan further activities after your arrival in Interlaken. The 2nd day could indeed be used for the
roundabout trip in the Bernese Oberland. As no hiking is involved, the weather won't be that much of a problem. But a clear and sunny day would of course be preferable, as the views are absolutely amazing. Bad weather alternatives would be the
Trümmelbach falls and the
Aare gorge - less scenic, but still impressive. It can't be predicted what the weather will be like in November. It can be very clear and sunny, but early winter, snow and clouds are possible as well. Therefore it's always wise to have some alternatives in mind and keep your travel scheme flexible. As for tickets and the best pass to buy: I'd say a
Swiss Half Fare Card would be best in your case. A Swiss Saver Pass offers ease of use, as you can travel for free in train, bus and boat and as you don't have to purchase regular tickets for these trips. But then again, a fairly large portion of your trip will include cable cars and mountains trains. These aren't for free with a Swiss Saver Pass. Most are discounted by 50%, but some (including the mountain trains between Grindelwald, Wengen, Kleine Scheidegg and Jungfraujoch, which you'll be using) are discounted by 25%. Moreover, you won't be travelling very large and expensive distances, so a Swiss Half Fare Card is very likely the most economical solution. You can purchase your Swiss Half Fare Card in advance through the
Swiss Half Fare Card page. Pick your country of residence in the list under the header 'Order your Swiss Half Fare Card here'. During the order process you can also indicate that you want to receive a free STS Family Card along with the pass, which will indeed allow the children to travel along with you for free on all trips. If you have a Swiss Half Fare Card, this means that you'll have to purchase reduced tickets for all trips you want to make. This can easily be done at the spot right before boarding the (mountain) train, at a ticket corner or at the ticketing machines which have clear instructions in English and allow you to purchase half fare tickets.
3) Several train connections to Paris are available. The trains to Paris leave from Zurich, Basel and Geneva. It's best review the
page on train travel between Switzerland and Paris (just fill out your departure station - Zurich, Basel or Geneva - and your arrival station - Paris - in the timetable displayed here) and see what the best and most convenient connection is. If you decide to travel through Basel, it's very easy to visit Bern on your way. Some tips for a short visit to Bern can be found on the
Bern tourism page. If you choose a connection leaving from Zurich, you can easily combine visits to
Lucerne and Zurich. And if your connection runs through Geneva, you could visit Bern, Lausanne and/or Geneva on your way. Zurich, Bern and Lucerne are all worth a visit. Hopefully the links I gave will help you to make a decision.
I hope this helps!