iMovie comes built in and is good for learning the basics. However, FCP is the mutt's nuts when you get into advanced stuff.
Good question. Can't remember and I'm not at a Mac just now. What you do in FCPX is to click on speed editor and then reverse motion, so I'd imagine that iMovie would be the same.
Hmm I'm not familiar with iMovie to know where to look, and don't have FCPX
U.K. London Side pushing the Phantom 4. Peace