I haven't read that one yet! I'll check it out. ^_^
To answer your questions:
-no poly routes in this story
-you'll have to find out :D
-healers are assumed to be creating tonics and such but it doesn't play a huge role in-story yet
-backgrounds dictate how certain events play out for your MC and add different flavor-texts. For example, how a physical altercation plays out (if your MC has one) is different if they are a healer versus, say, a tree cutter.