1) Can Dobryn use any form of projection on your character's mind? God's pretty boss so only if she allows it which won't happen if she thinks he's going to be harmful. If he just wants to use it to talk then she'd let him.
2) If yes to the above, is there anything Dobryn should be immediately aware of should he attempt projection into your character's mind? She's powerful and old. It might be a little overwhelming.
3) Can Cavatina interject in any form of telepathic communication between Dobryn and your character? Yep! The more the merrier.