Hi, as someone mentioned above, I too find the SBB site lacking and to me as someone never using it before, not very user friendly. There seem to be so many pricing/ticket options, I'm completely confused.
Here is what I'm try to do. I'm hoping someone can lend guidance.
My wife and I will be in Switzerland for about 1 week (our first time).
The agenda is arrive ZRH in the morning. Take the train to Lucerne.
3 days in Lucerne.
Train to Lauterbrunnen.
3 days in Lauterbrunnen
Train to Zurich for 1 night
Train from Zurich to ZRH in the morning.
Keep in mind while in Lucerne, we'd like to visit Mt Rigi and/or Pilatus etc. While in Lauterbrunnen we'd like to go to the mountain tops, Jungfrau etc. Some passes give you discounts on these things and some may be included?

My questions/issues are two fold-
1. What is the best pass for us, if any?
I'm trying to figure out if the Swiss Pass or something else makes the most sense. I did email SBB and they suggested the Half Fare card. OK fine. How does it work? I can only buy it 2 months in advance and then what do I do?

2. Once I have bought my pass what's next?
Assuming I can buy it online, and once I have it (some kind of ticket number I assume vs and actual 'card') can I then begin to make reservations?

Do I need to make reservations in advance? Or, are we better off just showing up at the station and buying a ticket? What about seat assignments? Sounds like they're not needed? I'm reading catandmouse's comments above but I'm still stressing about it a bit.

Please be kind. I am admittedly a train travel newbie.
Thank you