1. Will we ever be able to sync our Empegs with the Karma so when I do get my wife one it will be easy to keep them both up to date? (I assume/hope that someday the Karma will get nested playlists, otherwise this couldn't ever happen)

Aye, there's the rub. None of the other products have hierarchical playlists and therefore you can't get the empeg in synch with them.

I don't know if it will ever happen. I was hoping for something like this for the Rio Central and it hasn't happened. I recently re-did my whole collection, and I still have to keep things carefully organized, by hand, between the PC, the Central, the Empeg, and <whatever else I have>.