I haven't read the full thread so apologise if most of this has probably already been suggested.
First off, if he's doing tae twondo, have a chat with him about the tenets and how they should apply to life in general, not just in the dojo. (Or if you want to be really mean, ask the instructor to do that in class, although I wouldn't at that age). The main ones you should be seeing here are courtesy, self-control and integrity. Although, the main one I saw was way too much indomitable spirit ;-).
I have no problem with the kids helping themselves, within reason. That means they can have what they want from the stuff that is a free for all, like bread, fruit, yoghurt, cheese, eggs etc. However, they need to consider other people too. So if there are only 2 yoghurts left, they don't eat both. If there is something a bit unusual there, they check that it's not there for a reason.
However, I expect them to eat the meals they are provided with (within reason) and not to fill up on other stuff close to meal times. In the situation you describe, eating the bacon and eggs you had planned to use for another meal was not on. Leaving a mess was also not on.
Most 14 year olds can be reasoned with, but it requires lots of repetition. I would sit down and talk to him. Explain that money is tight and that you need him to get on board with your meal planning. Maybe get him to help with it.
My 16 meal old claims I am unbelievably cruel as I use the wi-fi as a stick to beat him with. He is told to do something (in your case, tidying up after himself). He is allowed a reasonable time delay, so if he says he will do it in 15 minutes when he's finished x, that's fine. he'll do it later is not. If it's not done by then, the wi-fi is turned off for him until it is done.