-Your Time Is Gonna Come was played shortly as a part of a jam-medley, i guess it was '72 at Japan? Never really played solely.
-I'm pretty sure When The Levee Breaks has been performed once or twice during the history of Zep. [Answered]
-And man, Fool In The Rain is a very, very cool song (albeit bit too similiar in all parts). Pre-Zep era: Plant perfomed it with Pearl Jam recently, at some charity gig.
Yeah, during D&C jams they would play a part very much reminding the WW.
In fact, i think Walter's Walk was inspired BY the D&C jams and it was recorded at Rolling Stones Mobile studio.
Played live or not - it's up to you.
-Carouselambra has been in fact played with In The Evening on No Quarter - tour (i gotta hear this version, it sounds bombastic). But yeah, never during Zeppelin.