This sounds like fairly common behavior for a boy that age.
In fact, it sounds an awful lot like me at around 13-14.
It may just be that he is testing boundaries, or it may be that he genuinely has an issue with doing his homework.
The first step I'd suggest is finding out why he hasn't been doing his homework. Is he bored? Is it too tough? Does he feel he doesn't have enough time to do it? Or does he just "not feel like it"?
Try to work to alleviate his reasons.
If it is too tough, talk about what options he has (tutoring, talking with the teacher, switching class tracks if necessary/possible, etc.).
If he doesn't have time, work with him to create a schedule for his week. This will help identify what activities may be taking up too much of his time, and help teach him some valuable time management skills.
If he's bored, you can look at ways at supplementing the assignments, either by working with the teacher, establishing your own criteria (i.e. add a research paper on some aspect of the topic that your son finds interesting), or looking for outside resources. This answer from another question provides some good advice.
However, finding out why he isn't doing the homework is only the first step.
You should absolutely keep up with the restrictions you've already put in place (loss of hockey privileges, other recreation, etc.) until he shows an appropriate level of improvement.
It sounds like he's shown some improvement, and you shouldn't underestimate that. You don't indicate whether the 10 zeros in math were from before or after you reinstated hockey privileges, but if they were from before, I'd consider letting him play unless he misses more assignments after he starts back up. It would be a bit harsh and discouraging to earn back his privileges by putting effort into doing better (which it sounds like he has), only to lose it because of old mistakes catching up to him.
Most importantly, I suggest setting concrete guidelines for what is required from him in order to regain each privilege he lost. Its too vague to say something like "when your grades get better", or even "when you stop missing your assignments".
Be very concrete. Set rules such as "if you complete 100% of your assignments for all classes for the next two weeks, you can start playing hockey again. After that, if you miss more than one assignment in a week for any given class, you'll lose it again."
If there are certain classes he's struggling with, you may set goals/rules that account for that. Perhaps he gets some leniency in the classes he's doing well in, provided he puts extra effort into the classes he's having a hard time with.
You also want to make sure you communicate clearly and frequently with him. Be proactive. Ask what his assignments are. Talk to him about what times he plans on working on his assignment, and respect those times (perhaps bring him a snack while he's working to show support).
As for drawing on his clothes, well... I wouldn't read too much into it. I remember that lots of kids in my school drew on their clothes, myself included. All I suggest doing is be very strict in that you won't buy him new clothes just because he decided that he didn't like how the drawings turned out. Being short on clothes, or forced to wear something that has been "decorated" in a way that he no longer likes, will drive home that lesson pretty quickly. Of course, if he legitimately outgrows the clothes, then they can be replaced as normal.
