1. Check the website for course requirement. As far as I remember, there are certain selective courses.
2. As far as I know, there is no separate concentrations. There are courses in computational finance inside of the Stat Department. I know one person who is planning to apply for Finance PHD after getting Stat MS at the UW.
UW Biostat Department is in School of Public Health, whereas Statistics Department is in College of Arts and Sciences. If you want to apply for BioStat MS, it is a different program.
3. I don't know any international MS students who have graduated and where they went after graduation.
I heard that one person is working at Boeing after obtained her MS from UW. She is not Chinese.
I think most Stat programs would like to admit applicants with solid mathematical and statistical background.
Without knowing the level of the courses you have taken, I really have nothing to say.
Although I do know the background of two persons who got MS admission last year, I don't think the information is helpful for you since both of them double-majored and one of the majors was math.