It is a risk, but it's still true that the Indian vegetarian diet will cover all major dietary needs. And while that's not the most ringing endorsement, it's more than you can say for cutting meat out of a diet that features a lot of meat.

How much dairy protein is in such a diet? A lot of the curries I enjoy have yogurt and I love the cheese and cream in palak and saag paneer. But those may not be normal dishes?

I don't know, though my first guess would have been that the major source of protein would be lentils or other pulses. Yogurt is certainly plausible as well.