Questions about Ms. Meade, Myrtle and Nan

So I'm pretty disappointed that Cordelia hasn't made any mention of bringing Nan back. Why not demand Michael bring her back as well? Or why didn't she herself bring Nan back after fully realizing her power? The only thing I can think of myself is that Nan didn't actually go to hell when she died and Michael can only go to hell to bargain for souls. If that's the case, demanding that Michael bring her back would have been a good way to rig the game against his 'promotion.'

Are they ever going to address the circumstances of Myrtle coming back? There are solid theories out there but it would be nice to actually know. Glossing over it is irritating given how the character ended in Season 3.

I'm really interested to see what actually happened to the human Ms. Meade. I'm assuming it has to be something other than simply getting killed off since we've seen Michael demonstrate resurrection even in the most dire of circumstances ala Misty Day. Why make a robot if he can just bring her back?