Re: How exactly did Clara "save" the Doctor.
The Doctor Who Magazine
review pointed this out as one of the problems with the episode; you can read Graham Kibble-White's (well-written) take here: http://whoreview.wordpress.com/2013/...of-the-doctor/
"En garde, you microscopic misanthrope! Ah, we shall call this adventure 'The One Where Larger-Than-Life Heroes Come in Small Packages.'"
Science's Less Accurate Grandmother