I would say, become friends with the staff and your teachers. This will help when you come out.
As far as coming out......
This can be really hard, and everyone is different. Personally I would do letters. That's how I told everyone. Maybe you can write a speach. Go with feels to most safe for you.
As far as their reactions.....
Some may be cool with it, others just don't care, and yet there may be that few who will hate you. Just remember, haters always be haten. You are doing what you need to do to be whole. This isn't for them. This will help you find out who your REAL friends are.
But what ever you do, don't wait. I was 14 when I figured this all out, and yet waited 20 years because of fear and being ashamed. You have a chance do what you need to do.
Best of luck!
~Emily King