Can you bring your own food into Delta Airline Plane?

Not like a meal but certainly snacks and stuff

Agricultural products (meat, cheese, fruits, etc) may not be allowed in the country at the other end of your flight, so you may have to consume them or throw them out at the checkpoint IF they search and find them. I had to throw out a Slim Jim going into Germany once... I don't even think that has any real meat in it! Also, you are restricted to 3 oz of liquids or gels, and drinks are not normally permitted, so stick to solid food items and you should be just fine.

Yes, within reason.

You will not be able to use their equipment to heat up your food and you are pretty much limited to what you can carry on in your carry on bag. Don't bring anything that will disturb other passengers - nothing really fragrant or obnoxious.

Yes as long as the food doesn't disturb the passengers.

VERY IMPORTANT BELOW!

All food must be naught IN the airport! You can find snacks and stuff in the airport don't worry

If you can get it through security, yes. Liquids are definitely restricted from going thru security.