Yes you can. Nothing with glass and the is a size regulation on coolers. https://disneyworld.disney.go.com/faq/parks/outside-food-and-drink/
Directly from Disney - https://disneyworld.disney.go.com/faq/parks/outside-food-and-drink/
Yes, you can bring your own food there. In fact it is highly recommended, because prices there are outrageously high.
You can bring anything non acholic
Yes you can. I'm not sure what are the limitations regarding food but usually small snacks or sandwiches are fine.
Thanks! Your answer is awaiting moderation.