Laziness is something you'll have to want to overcome, the best fix for you is apart from exercising some self will, you'll need to replace your bad habits with good ones, or at least acceptable ones.
Your sleeping habit, this isn't abnormal for teens. When you go to sleep, can you get to sleep or do you just stare at the ceiling?
Your homework, well put it this way, what do you want to be in life?
Your weight is a much more easy solve. Everyday try and go for a jog/run or a bike ride. If you do that for 30 minutes daily, it will help you get to sleep earlier, it will make you more fit and also reduce your weight, and it will also make you more active.
Also your diet is very important, cut down on ALL the junk food for the next month and that alone will see weight drop. Better still try to eat fruits daily, and salads daily, they're very nutritious sources of energy with low calories. If you get to like these types of food you'll be on your way to becoming fit and healthy.
I would not suggest you go to the gym at the moment. From reading what you've said you seem like the type of person who after a gym workout will just eat some junk food, which will completely nullify the effects of your workout.
The solve for your problems is becoming more active, by riding a bike, running, jogging, even playing a sport.
The hardest part is for you to want to, that comes from within. You have to motivate yourself to want to lose weight, to want to sleep earlier, to want to get good grades. If you don't want those things hard enough, then you might as well stop now.