Importing movies to purple iMovie from iPhone, iPad, and iPhoto

I have created movies on my iphone and on a Lumix camera. I am trying to figure out the best way to have all my movies in iMovie rather than iPhoto.

I have already likely made the mistake of transfering my Lumix data to an iPad with iOS while I was in Asia. In retrospect, I suppose the best way to get those pictures from my iPad to iMovie would have been to not export the movie from my iPad to my Camera Roll and into iPhoto but rather from my iPad to iMovie.

I also suspect that my iPhone pictures seen on Photo Stream on my iPad would have been best exported to iMovie and from my my iOS iMovie App to send to my Mac iMovie application.

Are these two ideas correct?

However, some of my movies are already imported into my desktop iPhoto. So, I tried dragging and dropping to my Mac's desktop. I then imported my movies (that came from my iPhone) into my Purple version of iMovie. That was fine except when I trashed my desktop movie to the Trash, it became greyed out in iMovie. So, next question is what I am doing wrong at this point?

Next, my movies from my Lumix imported into my iPad were also then transferred to my Mac OS iPhoto. I dragged those pictures to my desktop but the format is not xx.mp4 but rather is xx.MOV. Is there a better way of dealing with my iPhoto xx.MOV's to get them into Purple iMovie?

Finally, should I just leave all my movies in iPhoto and when in iMovie desktop just view them from the Aperture or iPhoto sidebar? Can they or should they be imported from the sidebar into iMovie? If so, can they safely be deleted from iPhoto or will my iMovie clips return to being greyed-out?

I would ideally like all my movies in iMovie and not have duplicate movies in iMovie and iPhoto.What is the best way moving forward to do this properly and to be optimizing my time and organization?

Thank you