It most naturally gives the location of the action: the speaking is happening in the waiting room.
In practice, that usually also means the nurse is there too. French, like English, often leaves this slightly flexible unless more context is added.
So the phrase works like an adverbial phrase of place:
Actually, the word order here is quite close to English:
So French is following a normal pattern:
subject + verb + indirect object/prepositional phrase + place
This is very common and natural in French.
It can mean either, depending on context.
French present tense often covers both:
French does not always separate simple present and present progressive the way English does.
Usually, no, if you mean speaking to the patients.
Both can be correct in some contexts, but they are not exactly the same.
So:
The second version can suggest more of a two-way interaction. The original sentence is perfectly standard.