First thing is first, your friend: Be there for them, but don't impose. Listening is better than doing anything at all sometimes. Don't forget about your own welfare as well, it's no good if you both are stressed. And please, don't blame yourself if you cannot cheer them up. They are going through their own struggles as well as you are. Support each other but don't think you are to blame for not doing enough; you are only one person after all.
Other people; Yes, people can be absolute bastards. You could say they are the reason I fell apart. Unfortunately, fighting them will just spout more trouble, and these types cannot be reasoned with. Try not to give them a reaction. If they cannot get anything out of you, they may leave you alone; of course, you can report them to school authorities as well, especially if the reason they are harassing you is demographic. Don't worry about being tough or a snitch or something stupid like that, the sooner they stop the better. If all else fails... Just try to be cool about it. They'll be the ones looking stupid if they are being obnoxious without anything to gain. And remember that you will probably never see these idiots again after school ends; if they don't change they'll likely end up alone or in jail anyway.
This girl you like; I would take this two different ways depending on your relationship with her. If you're already friends, find the right moment and forwardly confess. It's cliche, but if she says yes, you're set. And if she says no, atleast she knows and you were brave. Who knows? She may think about you again at a later date. If you're strangers, try to approach her casually, take things slowly. She may get the wrong idea if you come on strong and she's a shy type. Most importantly; don't do anything Teddie or Yusuke would do.
(Continued...)