>> Where is it best to sit on the train on the way there and the way back?
For the best view of the Landwasser Viadukt, the glaciers, lakes, and the Brusio circular viaduct, sit on the right heading towards Tirano, and on the left facing backwards heading towards Chur.
You have the best chance of choosing your preferred side of the train if you travel on a regional train that doesn't require reservations, so I would travel at least one direction on a regional train. Take daylight hours into account when choosing your connections.
>> Do you think it's a big risk going for the 7.07, I don't how big Chur Station is or how often the trains run late?
If arriving from Zürich on the 6:37 or 7:07, you will arrive on Platform 9. The Bernina Express departs from Platform 10 - the other side of the same platform.
>> Where would you advise sitting on the Bernina Express on the way out and on the way back, both in terms of left and right and front, back, middle of the train?
If you sit towards the back of the train (heading towards Tirano), you get better views of the front half of the train going round curves, especially when you get to the Landwasser Viadukt and Brusio circular viaduct. Coming back the other way, if you are facing backwards, being towards the front of the train is better.
>> Here's the best place to buy all of the tickets?
You can buy your tickets (Zürich-Tirano) plus reservation (Chur-Tirano) on the Rhaetian Railway website.
Alternatively, you can buy tickets and reservations separately:
- Tickets on the Rhaetian Railway or SBB websites, or at any station in Switzerland. If buying a ticket from Zürich to Tirano, choose the option Via VEREINA ODER ALBULA.
- Reservations via the link Lucas has given you, or directly on the Rhätische Bahn website:
When making a reservation, if you already have a ticket (or intend to get one separately), choose the reduction "Ticket available". The reservation will cost CHF 10 per person one way.