Hi OP!
My name is Maxime. I was in your exact same situation two years ago when I started to look into American colleges. I went through the whole application process last year so I hope I can be of help here. I know that the prospect of attending MIT is extremely appealing but, as MYOS said, it is important to look into safety schools as well. The American application process is a fascinating one but be prepared to spend hours and hours on it.
I have a vey busy summer so it would be difficult for me to write a detailed, general message about it but I’d be happy to answer specific questions! 
You can also PM me if you want so we can chat
(I’m French too btw)