Unfortunately, these are questions that can't be answered without further information, either from the game or the writers. Many folks have mentioned the Halsin thing in other threads. Apparently a similar thing happens with Shadowheart (who has the same writer) if you resolve her quest a particular way. I have no idea why the writer would decide to end things like that (and only for one of Shadowheart's endings!).
There's no indication that the other thing would work. Mizora shows no interest. There's no way to bring up the subject. The game just doesn't acknowledge such a possibility at all. Again, we'd just have to speculate.
