I was wondering what protection / cover / insurance / safety I should be looking for and expect from a mountain biking tour/destination company? What precautions should I take myself?
To start with, you should ask the company before you pay.
On the other hand, it really depends which area of the world you are going to. Law and customs are quite different in different areas of the world. Whereas in the western countries I would expect the operator to have some basic level of insurance cover for accidents, I would expect exactly the opposite in most of the developing countries. You still should double check with the company (guide) to make sure that the level of cover is satisfactory for you.