10. For the most part, yes. I think they're largely lucid dreamers, so it follows that the memories are more vibrant, though still...blurry in a dream way? It's hard to make sense of a dream once you're out of it.
He saw her face with everyone else when he was first starting to regenerate, before his memories were properly restored. Pieces of her are still there, in his subconsciousness. He can access them when he's sleeping; they're gone when he wakes up.
15. When I say "largely" - he knows he's dreaming, he can direct his dreams, but he doesn't control them completely and can't just choose what his mind throws at him. (Could he try harder to quash certain nightmares than he actually does? Yeah probably.)
About a lot of worlds, really. Particularly in Duplicity, I think; he can't access the vast wonder of the universe at the moment, but he can dream about it.
i really just want him to cuddle barry