Hey,

of course you need a pass day if you want to use a train with your Interrail pass. Even if it is just a train from Zürich HB to Zürich Hardbrücke. But in such a case of course it will be cheaper to buy a single ticket (or daypass for ZVV) instead of using an Interrail pass day.
Best to compare prices on sbb website with how much it would be for one day of your pass.

You don’t need reservations. Nobody in Switzerland makes reservations (except bigger groups and foreign tourists) and still they always find a seat.

As said : any train fully included requires a pass day. On a pass day you may board as many trains as you wish. Eurail is valid on boats on Lake Thun and Brienz btw!

When you get a discount (50% on Pilatus and 25% on Pilatus for example) you do not need a travel day per se but you'll probably take trains to reach the cable car/mountain railway departure => travel day needed.

Check timetables on SBB app : reliable and useful.

Which train do you mean between Zermatt and Milan ? You could take part of the Glacier Express route on regional trains (as far as Andermatt) but it's a detour.

The fastest route is a EC train from Brig to Milan. Reservations are mandatory and cost 13€. When is your journey planned ? Part of that route will be closed from 9th June to 8th September for works. Rail replacement buses run.

Thanks for the clarifications! I'm choosing between getting a 5 days travel pass or 7 days travel pass as my travelling would require 6 days so I'm deciding should I buy a separate ticket for 1 of the days instead and get the 5 days pass or just save the trouble and get the 7 days.

I read somewhere that I can take Bernina Express (Panoramic train) from Swiss to Milan. From Chur to Tirano (and subsequently take a local train to Milan). Not too sure if that is possible and even make any sense. Any advice on that?

Anyway, I'll be travelling from 14 Feb to 1 Mar so I think I won't be affected.

By the way I just tried booking a ticket via the SBB app, I don't see the pass selection of Eurail Global Pass, any idea which one should I choose to get the correct price? Thank you so much in advance! 

Zermatt - Milan via Andermatt and Tirano would be a huge detour (Glacier Express + Bernina Express on local trains), unlikely to be possible in a day. However you could stay overnight in Chur. It's a stunning journey though!

Otherwise a good compromise is :

- Zermatt - Visp - Andermatt (Glacier Express route on regional trains)

- Andermatt - Göschenen - Locarno (worth a little break)

- hourly reservation-free RE to Milan

Fully flexible as you won't need reservations. :)

What are you trying to book ? SBB cannot sell passholder reservations to Italy and domestic reservations are a waste of money, nobody makes them.

That's a great suggestion! Thank you! Any idea if I will be able to reach Milan by say 3pm on the 1 Mar if I leave Zermatt in the morning?

I'm actually trying to make a reservation for Paris to Lucerne on the 23rd Feb so trying to figure out how to exactly do that via the app which later directed me to the website. Any idea where should I actually make my train seat reservation from? 

TGVs are currently best booked on www.raileurope.com: no booking fees and you can give seat preferences, like upper deck. For other reservations, look here:

https://www.seat61.com/interrail-and-eurail-reservations.htm

For timetables, look on www.sbb.ch for Switzerland (and many international journeys) and www.trenitalia.com for Italy.