3400 CHF / month (net) for 1 person. Sounds good?

Anyone please??? The point is that I'm finding too much contradictory information meaning that some people say that I'll starve with that amount while some people say that I'll be rolling in it

The correct answer is that you'll be fine. It depends where you are from and what you're used to in terms of standard of living. 3.4k CHF will not be rolling in it at all but it also won't be scraping by depending on where you live. If you find a flat with some flatmates, you can stay around 1k/mo for something dece which gives you 2.4 for food, assurance, etc. Bottom line is you're good unless you like buying bottles at clubs.

You won't have a new, 65sqm+ apartment alone, and you won't be able to eat out a lot. But otherwise you'll be okay. That's a standard phd salary actually. You can pay your assurance and everyday food from average grocery shops, you will be able to pay your rent. You won't be able to save much. And don't be too sad, there are vouchers and sales and coupons and such

Hi! - the answer depends on a lot of parameters - where will you live? more city or countryside? what is your lifestyle? exuberant or frugal? what do you want from life? learn a lot or amusement? etc. etc.
Kind regards - Alec

It should be OK if you share a flat and don't have a car or kids. A car isn't really required, we lived here for 3 years without one. The big expenses will be food, flat, and insurance.

ETH has a board for rooms for rent. Comparis.ch will give you insurance quotes. I'd recommend living close to campus so that you can get together with other grad students and study.