1. It could be either, and should be clarified by contextual clues.
2. It means walking around inside the room. Walking around the outside would require a continuous hallway encircling the room, which is not very common.
3. As with number 1, it could have either meaning and would be clarified by context:
He walked around the restaurant, greeting the customers and shaking hands. (inside)
He walked around the restaurant to the back lot where his car was parked. (outside)
Student or Learner