Housing is by far the biggest expense in DC, so if you have somewhere to live for free, that's an incredible gift. The debt thing is personal, but in my calculus, 60k is reasonable. I'll be clocking in a bit below that, so obviously I'm a little biased! But again it depends on your age, your lifestyle requirements, your 5-year-plan, what specific field you're looking to enter...
In terms of it being 'worth it' in general, in DC a master's degree is basically a requirement to move up, as you may know. So if you want to go into IR, you're almost certainly going to have to pay for a master's eventually. The SAIS network has been great so far, although of course I have only done information-gathering and internship-hunting at this point. I haven't had one alum I've contacted fail to get back to me and offer to at least answer my questions via email. The help you get from SAIS in terms of career services varies based on your needs and your concentration - my concentration has been great about helping us find internships and giving us summer funding, but some students have complained about lack of help in theirs. I think a lot of it is about a willingness to take advantage of the resources being offered, but that's just a personal philosophy/personality thing I suppose. Also it really does help if you have (preferably relevant) work experience, even if it's only a year at a local non-profit.
Regarding working while in school - are you talking about DC or Bologna? At both campuses, courses only meet once/week, so you could try to arrange your schedule to have some free days. In DC, I know that many students have internships or jobs (full or part-time), and there are a good number of classes offered at night as well, although I'm not sure if that holds for language classes. If you can pass proficiency upon matriculation, you won't actually need to take a language. In Bologna, there aren't as many night-time classes, and languages are only offered during the day (but just on Tuesdays, Wednesdays, and Fridays - so I suppose you could work on Mondays and Thursdays). But I don't know any students who have non-campus jobs (other than working remotely for former employers), but it's possible I suppose, assuming you have work authorization in Italy.