In terms of "what is home", i typically use the "scopes" app rather then the dash. For me, on the phone, the dash is just a place of shortcuts for apps that I open a lot.
There's no real value in the empty background right now - nothing there i cannot do from elsewhere except see nothing. If convergence comes, then putting stuff on the desktop makes sense (if we liked gnome, we wouldn't be here). Or, setting a default home app could also work (and then you could default that to a "desktop" app that shows shortcuts ...).
If any real option gets coded, we would indeed need a way to get there. Swipe left is for the drawer (and apps), which is a change I'll at least have to get used to instead of accessing the scopes app in the spread. You could put a desktop icon on the drawer somewhere, which would re-inforce the drawer as the unit of navigation. You could also put both the open drawer (as a replaces of the scope app) as well as the background as defaults in the spread. You could also just do both.
Concerning the "click outside" from the spread: it's a new form of interaction. It might be more intuitive if there's a card to select from, and if that card is always at the same place.
Also, "hide apps" sounds wrong to me. I want to (positively) go home, not (negatively) hide other stuff.
