Disneyland started offering housing last year. I believe it may limited and I'm sure it's not cheap but it is available.
Disney College Program: Disneyland - Students: Housing Overview
I wouldn't worry so much about deciding exactly what major and exactly what you want to do with your life because these things will change as you age and have different life experiences. When I graduated from high school I wanted to be a floral designer. I did this for three years till I got burnt out and it was time for a change. I was really glad I had the opportunity to do this because even though it was not a lifetime career I got to do something I'd always wanted to do. Now I'm almost thirty and I'm on my third career.
Disney is a huge company with literally thousands of jobs. Career paths tend to take many different directions.