Try to talk to him, when he has calmed down. State firmly that he will not have access to any of your money. Make sure your bank card is secure. Do not let him near it (he may copy details onto his phone). Explain that, at 16, perhaps he could begin looking for P/T employment. Keep cash on you if possible.
If he is in the cadets, he may have ambitions to join the forces. If this is so, explain, calmly, that a criminal record will be detrimental to this aim. Reassure him that you will pay for whatever he needs, but stealing is one step too far.
If he is addicted to the X Box, then it is important that education and the cadets are maintained. Ask him calmly about the bullying. It may be an effort to deflect, but it could also be a real problem for him.
Tell him that it hurts you when he calls you names. Tell him this when he is calm.
He probably does have some underlying issues, especially if he did this as a pre-teen, and if he struggles to make friends or connections.
My son has many of the traits you describe. He is a few years older than your son, and is now receiving MH support. My only way of coping sometimes, is to treat his behaviour logically, and maintain damage limitation.
It is really hard, but we can take strength from @JustBeKinder 's post; our sons may very well come through this as much more well balanced people.