Analyze the part where the dream shifts, because I have learned through analysis that the "phase change" is significant. What did you do to cause the change and then what happened immediately after? Why do you think that happened?
In my personal experience, if I "test" an entity with a pentagram and it doesn't react negatively, that's usually a good sign, but go with your intuition. I have tested entities and received very negative reactions, so that becomes pretty obvious to discern. You can also interpret everyone you encounter in the dream space as part of yourself, as said above. I think it's a matter of convenience.
Next time you go to sleep, you could seed the intention in your mind to pick up where the dream left off and see what happens.
