The Key to Time the Stones of Blood episode it may just answer the questions. Romana was pushed over the edge of a cliff by who she thought was the Doctor. Much later when the real Doctor used K-9 to locate her he used his scarf to pull her up and the following conversation takes place.
Romana: Get away from me.
Doctor: What’s the matter?
Romana: Who are you?
Doctor: You know very well who I. Well K-9 who am I. Well go on, K-9. Tell her who I am. K-9?
K-9: Cross-checking. You are the Doctor Master.
Doctor: There you are. I’m the Doctor.
Romana: Well, if you didn’t push me over this cliff then who did? And believe me it was no projection. You were solid. It was solid.
Doctor: It looked exactly like me?
Romana: The image of you. [You then hear a noise in the background. It is the same noise that you hear when a segment is transformed from it’s disguised self to it true form using the tracer. It continues throughout the rest of the conversation.]
Romana: The power to transform objects or at least their appearance.
Romana: Somebody’s got it and they’ve found a way of utilizing its power.
So is this where they got the idea of Smokey being able to take on different forms? Is it also the reason why there is a sound that is heard when he is in the local vicinity?
1 May 10 6:37 MST
[Correction: The sound that was made was the sound of the Ogri monster as it feeds on blood]