Islamabad is expensive, but it's worth the money. Very nice city, very clean and nice people. Accomadation shouldn't be a problem, depends what hospital your at. If there's a medical college attached you might be able to get accomadation in the hostels, but it depends. As for food, plenty to choose from, plus you have Rawalpindi next door to get all your shopping done. And yes it's safe...the whole country is safe, I'd suggest you not listen to BBC and CNN as they tend to overexagerate news, especially when it concerns the Middle East and Muslim countries. Hope that helps.

Have fun.