iPhoto won't allow me to download some of the photos off my iPhone/Deleting photos already imported to iPhoto from my phone.

I am running iPhoto 11 on a 17 inch Mac pro, and my iPhone is an iPhone 4 running iOS 6. I have 6,926 photos on my iPhone, and it has finally run out of space. I decided to stop procrastinating and export the photos to iPhoto. iPhoto was able to import about 3,920 photos, but couldn't import 622 of the rest. When I tried to import those 622, I got this message.

Then I tried downloading an image at a time, to see if there was one corrupt image corrupting the rest (I knew this wasn't really all that possible, but I wanted to try it anyway.) Alas, it didn't work.

As you may have noticed, 3920+622= 4542, not 6926. I think that the 2384 photos missing were in my library from using the iCloud photo stream.

But anyway, how do I fix the importing problem?

And most importantly (for me,) how do I delete the photos I've already imported off my phone? I want those 3,920 photos off my device, simply to clear up 9 gigs of storage.

Thanks.