here's the 10-11 fee schedule:
http://finance.unc.edu/images/stories/saur/10_11_tuitionfees.pdf
the numbers may vary slightly for 11-12, but as a non-resident (full-time student) it would cost you approximately 12,000 in tuition & fees for the academic year. then you'd have to add costs for books, food, rent and living expenses (depending on your lifestyle this will vary widely between students).
RA positions are generally reserved for PHD students, but master's students may obtain RA positions on a limited basis--depending on the needs of the PI for the project and if they are interested in working with you.
TA positions are available, but from what i understand, are more common among 2nd years. professors can either give the financial aid office a list of qualifications they desire in a TA, or they can specifically select a student who they would like to TA their course. often students are selected to TA specific courses, which is why it's more common among 2nd years. TA positions generally provide a $5,300 stipend and cover tuition and health insurance for the semester.
depending on your background, TA positions are also available outside of the school of public health. i.e. if you majored in biology, you could potentially be a TA for an undergraduate biology course--these TA positions also come with the same stipend and benefits.
In order to be eligible for an RA or TA position you must first fill out the HPM financial aid form.
you can find last year's form here:
http://www.sph.unc.edu/images/stories/academic_programs/hpaa/documents/aidform.doc
and last year's memo here:
http://www.sph.unc.edu/images/stories/academic_programs/hpaa/documents/aid_memo.doc
as far as i know, this year's form has not been released yet; however, i would imagine the information requested is very similar to last year's form. looking at the date on last year's memo, i'd assume this year's memo will be released and sent to all admitted applicants shortly.
some grants and awards are given out from the department based on both need and merit. the priority deadline to submit all of your application materials to be considered for a merit award is generally either 12/1 or 1/1. if you submitted your application after this deadline, then you may not have been considered for a merit award.
*this information is specific to the HPM department, and may or may not be true for other departments within the school of public health.
-waystinthyme