Thanks for the clarification. It helps a lot.
Arno has answered your questions about passes.
I thought to add a brief comment about the trains.
The time table that Arno linked you to can be very helpful, and the SBB (Swiss Rail) website has a tremendous amount of information available on most all aspects of rail travel, buried down in multilayer menus. ;-(
That links you directly to the timetable.
This is for the whole SBB site:
The trip - Zürich Airport to Interlaken Ost (IO) and thence afterwards to Geneva:
There is very very frequent service from the airport to downtown Zürich, so that your stopover can be at an airport hotel or in downtown Zürich. Some trains from the airport to Interlaken route directly to Bern and then to Interlaken. Most, however, route through Zürich main station and can involve a change of trains there. Zürich to Interlaken Ost is just under 2 hours.
A scenic and slower route to Interlaken is to travel via Luzern, then take the Luzern to interlaken 'Express" which travels over the Brunig Pass, and is part of the "Golden Pass" route. 2 hrs 51 minutes.
I don't know how much time you have or would like to take. Either Bern or Luzern is a possible stop for a few hours. Both are nice, but Luzern is more scenic right off the train. Let us know if you want to stop. There is a place for lunch in Luzern that I like a lot, along the river in the old town. Bern has one near the Nydegg bridge over the Aare.
When using the timetable, the default routing provided is the fastest route.
Alternatives can be forced by using the "connections" or "via" option, and inserting a midpoint, such as Luzern on the route to Interlaken from Zürich.
If you work with a map, that helps visualize these alternatives. This one is especially helpful for Switzerland:
Use of the menus and zoom on that map gives station icons, and gives a short timetable of transport from to or from that station.
You probably already know what you want to do whilst staying in Interlaken, but this may be helpful:
Interlaken to Geneva:
The fast route goes through Bern. 2 hours 48 minutes every hour on the hour. At each hour at xx29, a slightly slower route involves an additional change at Spiez.
The slower route follows the Golden Pass routing, going via Zweisimmen ( and, with that choice made) through Montreux. The section from Zweisimmen to Montreux is particularly attractive on the descent from Montbovon to Montreux.
4 hours 20 to 4 hrs 50 minutes. More changes of train.
Many of the trains after Zweisimmen have panoramic window cars to Montreux.
Sounds like you have created a very nice itinerary. Switzerland gives you some options to refine it, if you wish.
Quite a variety. Enjoy it!