I'm sure this is way too late to help any of you, but for future readers:
The BFA program (which is what I'm in) does require at least 3 semesters of voice (as well as 3 semesters of dance). More can be taken, and most people do take voice every semester. With the BFA, you are required to audition for all mainstage theatre shows - you do not have to have permission to audition for MT mainstage, Opera, Stripped, or Stage 2 shows - in fact, I would say that you are basically encouraged to audition for anything you can. They do want you to notify them if you are auditioning for places off campus, though most people only notify them once they have a role.
I highly recommend the BFA program. You have tons of required acting classes, plus some tech theatre classes, and various "book" classes on types of theatre. You are encouraged to take as much voice and dance as you can (though the dance school can really be a pain). In addition, you can take classes in the music school. A lot of theatre students take MT Workshop (it's excellent - I took it in the fall), and I know of a few that also take MT lit, and many of the theory courses.
Also, it is possible to get both the BA music and the BFA Acting degrees. You won't graduate for at least 5 years, but there are people doing both - the more common route, however, is taking the BA music with the BA theatre. Give the theatre dept. a call and I'm sure they would be fine with you switching to the BA degree rather than the BFA degree if this is something that interests you.
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as I come on here only about twice/yr.