Airports can be overwhelming. I almost always wear headphones outside anyway, and in a noisy airport, that helps.
To get on the plane, you need a ticket, ie a boarding pass. That's either printed, or on your phone. Anything else is insufficient. You'll get the pass when you check in at the airport, with a person or at a kiosk. You'll need your ID as well.
Airports are designed to be easy to navigate. An airport with thousands, or tens of thousands of people per day can't be too complicated or it causes problems. Imagine if 1% of passengers couldn't find their gate, with 10,000 passengers. They're made to be straightforward.
As for water, you can't bring water though security, but you can either bring a bottle and fill it at the airport. Some airports have bottle refill station, or you have to pay for a highly overpriced bottle of water past security near the gate.
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