1. You can use them both, they sound natural. 2. They're both right, but option B sounds more natural, and yes, you can say "El hombre con el que está hablando la profesora es el director", and I don't know exactly why but I'm sure you can use them indistincly. 3. You can use them both, they sound natural (again) 4. Yes, it means that 5. "Como decía" it's not "like I said" it's more like: "like she was saying" ("she" refers to Alicia). If you want to say "Like I said" it would be more like "Como dije or Como he dicho" 6. They are both correct, sound natural and I don't know the real explanation (again)