>> 1.The first leg shows up as a MOB train. Would all the cars require seat reservations or are there some 2nd class cars? (I’m looking at the 9:44 from Montreux.)
There are no compulsory reservations on any of the Golden Pass trains, in either first- or second-class, except if you want to travel in one of the 8 VIP first-class seats in the front carriage. These VIP seats are available on 2 departures daily in each direction - including the 9:44 from Montreux.
>> 2.i would probably go for the panoramic seats anyway and see where to make reservations on goldenpass. ch. Do I have to upgrade the travel pass to 1st class for that leg of the trip, and how do I do that?
Both first- and second-class carriages have panoramic windows. Do you actually mean the VIP seats?
To travel in the VIP seats, or normal first-class seats, you will indeed need to upgrade to first class for the sector Montreux-Zweisimmen (or to Montbovon if you are only going that far in the VIP seats).
You can buy a class upgrade at any staffed railway station in Switzerland up until any time before boarding the train. It will cost you half of the difference between the first-class and second-class fares for that sector. Here are the phrases for change of class for a sector in three of the national languages of Switzerland:
- German: Klassenwechsel für eine Strecke
- French: Surclassement pour un trajet
- Italian: Cambio di classe per una tratta
>> 3.It seems the seats reservations cost 8CHF whether we go as far as Montbovon or all the way to Zweisimmen. Once purchased, does anyone care how far you go—as in could we change our mind and go farther, or would those seats have been rebooked for the remainder of the M-Z leg?
Reservations are CHF 8 for the normal first- and second-class seats between Montreux and Zweisimmen, but CHF 15 for the VIP seats.
If you only reserve a seat from Montreux to Montbovon, it is unlikely someone else would have reserved the same seat from Montbovon to Zweisimmen, but you couldn't rule it out. If someone turned up with a reservation for that seat at Montbovon, you would have to vacate it.
It would be easier to reserve the whole sector Montreux to Zweisimmen, in which case your class upgrade would also have to cover the whole sector Montreux-Zweisimmen if you are booking the VIP or other first-class seats.
If you do decide to get off at Montbovon instead, that is OK. Reserved seats are released after 20 minutes, so if you are not still sitting in it, someone else can use that seat for the remainder of the sector if they want to.