Also beebee, I forgot to add - congratulations on getting accepted to the program! It's a huge achievement! I think I cut short my own celebrating by starting to think about all of the financial aspects, but it's good to remember what a great accomplishment it is.
I think the purpose of the first-year tuition scholarship is that it gives students time to look for external funding for years 2-5. One thing I'd like to find out from the department of how many of the current continuing doctoral students have been successful in finding external funding. As for living expenses, though the tuition scholarship doesn't come with a living stipend, I think that there are probably research assistant positions available through certain professors (or work study positions if you are eligible through financial aid, which may not be the case if you are an international student). However, the downside of these RA positions is that 1) I'm not sure if they would pay enough to cover all living expenses and 2) I'm not sure if we can arrange them beforehand, or if it's up in the air until we start the program and meet different professors. So, all good things for us to be asking the department as we make our decisions!