Currently Being ModeratedAug 7, 2012 8:00 AM (in response to LMM50)
You can check easily if iMovie will continue to work with photos after you've deleted them from iPhoto - simply make a quick project in iMovie and then delete the photos from iPhoto. I do believe they will but not absolutely certain.
No I don't believe you can share photos from LR to iMovie like you can from iPhoto or Aperture because LR has no knowledge or way of working with the Media Browser system. You'll need to export from it to the Finder and from there to iMovie.