Yes you can bring your own food to the airport and through security and on to the aircraft. Be aware that certain foodstuffs such as cheese might trigger a secondary bag inspection of your carry-on items.
Yes you can, put it in a separate bag to make it easier then put it in your carry on when you get through security.
I believe you can, not sure. I believe if you have a shoulder bag and if is sandwich or something like that, and you're not carrying the footing your hands. just water for some reason you can't bring.
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