I stayed at the Holiday Inn Express at 69 Boston Road. They have free breakfast, as well as a free shuttle to the BU medical center, and to the New England Medical Center (Tufts medical center). That hotel brought me good luck too; see
this thread for my story. As for your interview day, the way it works as that you have one 1 hour interview, and that's it. Your specific time will be assigned when you get there. After your interview, you can leave when you have to without any big repercussions. I was sick my interview day, so after my interview was over, I just told the secretary that I wasn't feeling well and just left before lunch and the tour and everything. I just got my acceptance letter yesterday, so my early departure didn't hurt apparently. Getting a 5:45 plane is really close. Even if you get out of the interview in time, you'll have to face rush hour traffic. I would recommend taking a later flight, or take an early morning flight the next morning if that's a possibility. Good luck.