As everything, it depends.
For most home videos, I would recommend that you shoot 30P with your camera. You will get great images.
However, if you are filming a sporting event like a soccer match or a football game with a lot of motion, you may get better results shooting 60i.
For workflow, you should attach the card from your camera to the card reader and open the iMovie import screen. There you have an option to Create a Camera Archive. This will place the entire contents of the card on a hard drive at the location you specify. You can then import into iMovie from the camera archive. I usually create an archive, then I import to iMovie from the Archive. If all is well, I will reformat (some cameras call this "initialize") my card using the menu on the camera so it is ready for the next shoot. These cards are formatted by the camera is FAT32, so I find if I do not regularly reformat them, they can get corrupted over time.
When you import, I usually would use the setting to import at Full Size (1920x1080). You can save some space using Large (960x540), but with 30P, you will get better results with Full Size.
Once you have imported the clips to an iMovie Event, you can adjust almost everything else nondestructively. (trimming clips, adjusting color, adjusting sound). Nothing you do in a Project will alter the physical clips in the Event.
It is important to realize that the physical clips are stored in the Event. The Project is simply a text file that contains an edit list of all edits and effects that are to be applied when you SHARE (or render) the project using the SHARE menu.
Thanks AppleMan for your help. This will help me a lot.
The only last question is the last part of your post.
When I share the project I assume that I need to pick the highest one. Is there a difference if I choose to export to QT pro. I Know that there's a bunch of diiferent options If I go to this route.
For most purposes, you can use the Apple presets according to your needs. These are 1920x1080, 1280x720, Large(960x540), Medium (640x480), etc. You can find these under SHARE/MOVIE which lets you place the resulting files wherever you want, or SHARE/iTunes (to iTunes), or SHARE/Media Browser (which makes it available to GarageBand, iDVD, Keynote, Pages, etc.)
These will be h.264 files with a great mix of quality and file size.
You can use SHARE/EXPORT USING QUICKTIME if you want to customize the export settings.
There are several reasons to do this. You might want to export in a different codec for a special purpose. For example, if you wanted to edit some more in a different application, you could export using Apple Intermediate Codec. You could export the audio only from your movie and make a sound file. You can also adjust the h.264 settings. It is unlikely that you will improve the quality by doing this, but sometimes people will do it to try to reduce the file size without decreasing the quality by too much.
Thanks Again AppleMan,
I've printed out the help you gave me so I won't forget.
I Also have a sony DV (mini tape) cam. that I use sometimes and I think It's a little more easier to heldle the files with that.
Again, thanks for the time you had to spend with me posting the awnsers and helping out, I appreciated.