You can't use Raw files for a movie. You'll be sharing Previews with iMovie. Just use the media browser in iMovie. Click on the Camera icon in the iMovie window:
Most times your preview quality / resolution will be >> DVD quality and there will be no issue with the movie output.
If for HD on an Apple TV or Blue-Ray (whenever) etc., then Preview quality/resolution may need to be checked.
To make sure, go to Aperture / Prefs. / Previews. Anything over Fits within 1920 x 1920 and quality > 10 (maybe as low as 7) should be fine. A little subjective here so your mileage may vary. Of course if you do change Preview settings, you'll need to regenerate an required Previews.
Just so I'm clear. I am using pix from different projects. So is your best recommendation to:
1. create an album in Aperture
2.Click on the camera
3.Download the album to iMovie
You can create an Album - or not - but creating an Album will perhaps make it easier to find the pics. You can access every single photo in your Aperture Library from the media browser.
You don't "download the album to iMovie". Just select a pic and drag into the project window.
Just launch iMovie and try it. 😉 There's less to this than meets the eye 😉