DF and I will being trying out for Fall

We are super excited and hope we make it.
I found out my school will let me get credit for the Human Resources class and 2 professional electives from Disney.
We would both like to audition for Character Performer but if that does not work out then the Roles I'll try for/ be open to are:
Attractions
PhotoPass Photographer
Character Attendant
Costuming
Merchandise
I know DF will probably put all those plus Transportation.
We are extremely excited.
The only thing that makes me nervous is that we have lived together for over 2 years and this would be our first time living with anyone other than our families or each other. It will take some getting use to.
How much is the difference (cost wise) of having more roomates; like say between having 3 room mates compared to 7 room mates. Is it a big difference cost wise. I know they say the lowest will be around $75 dollars for a week, so I was assuming that is with 7 room mates.