Yeah...usually when this happen they give them a private room so that their secret isn't exposed the very first day.
The entire setting for the character is basically just tropes. The whole "mysterious (and handsome) transfer student with an ominous/mysterious (and cool sounding) ability" is a massive trope in and of itself. The "is a girl who passes as a guy when wearing breast bindings and is attending the academy as a boy for family reasons" is another one that's pretty popular. Pretty sure it's much older than Infinite Stratos too. Both are fairly common in action/romcom series, though it varies whether they're present in the same series (let alone the same character).
She isn't the Principal's granddaughter. She's his friend's granddaughter. Decent odds the Principal doesn't even know she's a girl (heck, it could be the 'replacement' variant of the trope, where she's supposed to live as her brother/cousin/whatever).
Writing?
