What's the best video format to shoot in and import into an ordinary iMovie on an ordinary Macbook?

Last time, the freelance-student I used went through lots of time delays just trying to convert the file first, into one her iMovie would accept. She now just insists it should just be ".mov" but as I've read, that's just a 'container' and not really a format.

I'm shooting this Friday just for an amateur video, what format should I shoot in?

.mov, or .mp4 work pretty well. But iMovie will convert your video automatically to optimize it for the program. Just throw it in and let it do its work.