Question 3: You should be interacting with the doctor and patients when appropriate. The focus of shadowing should be on learning what that doctor does every day. It should be on figuring out if you can see yourself doing what they do. Medical training is long, hard and expensive. The reward at the end is getting to practice medicine. You need to have a pretty good idea of what that means.
Question 2: You should shadow long enough to be able to answer #3. It is hard to believe a 21 year old pre-med that says, "I want to go into medicine, I know what I'm talking about!" when their exposure to medicine is the same as how much I work in 1 week. 50 hours is a solid commitment, and 'good enough' for a single specialty/area of interest, but if you say, "50 hours with an orthopod, I know I want to be in medicine!" You almost automatically get thrown in the 'naive' pile.
