Swiss travel pass - Where to buy and how to use?

I'm from Brazil and I will spend a couple of weeks in Switzerland. I saw there are many questions about the Swiss Travel Pass but it seems there are no questions or answers regarding how to get it and how to use it.

1. Can I buy the Swiss Travel Pass at the Swiss airport or train station (I will arrive at Zurich)?

2. If yes, how long it will take to buy it? I mean, will it be easy as get there, ask for the pass, pay and get out (something like a few minutes transaction) or would it be a huge amount of effort that takes a couple of hours?

3. What kind of papers do I need to buy it? Is a passport enough?
4. Once I have it, how do I use it to buy the actual train tickets? Just ask for the ticket to the person selling the tickets and present the pass during the purchase?
5. If I decide to buy it online, do I need to print something and get the actual pass at some place? Or does the printed piece have the validity of the actual pass?

I know there are many questions here, but the are all in the same "package" of how to use the pass.

Here are the links I found about the pass but nothing about how to get/use it: Official website