As this question was asked in 2015, I hope you got through the interview and are successfully attending your programme.
I am in a similar situation, my course of PhD starts in Fall 2019. The university is offering me a tuition waiver and TA of $12,400 for 9 months. The total estimated cost is $42,000 and they are providing with almost $39,500 including the tuition fee. The rest has been covered by my family and a bit extra.
I am worried that I will have to show proof of funding for 5 years of the course, as I have seen in most of the forums for MS students. So my question is did u have to show documents of funding for 5 years of your course ?