Is he in therapy or counseling? He sounds like he has some issues and is not willing to share them with you. He needs a place, person he can be totally honest with.
Yes, this can be typical behaviors, but could be a sign of extreme depression also.
Just like when he was a toddler and throwing tantrums, you will need to be very strong and MAKE him follow the rules of behaviors in your home.
Decide what the consequences are going to be from now on.. and then sit him down and let him know, you are not kidding about this. You know he can behave and act his age. And so if he wants the privileges he now enjoys, he will have to change his attitude and behaviors.
Here are some suggestions.
NO eating or drinking in his room anymore. The reason? He does not properly dispose of the remains. Could he get this privilege back? Yes, if he can for a week keep his room clean of garbage. Can it be taken away? Yes, the moment the trash begins to appear.. another week without food and drink in his room.
Back talking, take the video games/TV away.. and I mean put them in the trunk of your car and ask a friend to hold them for you.
Can he get this privilege back? Yes, When he can go a week without talking back. Stomping around etc. Can he get them back.. Yes if for the week he can be respectful in his tone and behaviors.
He may also need his bedroom door removed. If he cannot behave his age, he may need to be watched all of the time.
The failing school. Are you working with his teachers and administration on this? Is it that he is actually failing the tests or failing to do his homework or all of it?
What is the plan? Is he in summer school? Does he have a tutor? Is there an after school program or can he take a supervised study hall?
I know this is very difficult for you to have to do all of this yourself.
You will need to be on the ball all of the time. Your son is sending out signals he needs help, he wants your attention and he does not even realize this.
Give him actual responsibilities.
Mow the yard, take out the trash, clean his own bathroom, help you with planning meals. Have him help you work on the household finances and help with the budget.
He can do this. He needs to know the truth about what you are all dealing with.. He is trying to be an adult, but he is actually just acting like a little boy. He is frightened, confused and probably exhausted from the depression.