how to save iPhone photos to iPhoto then safely delete from phone?

I have an iMac and an external drive on which i store photos, including iPhoto Library. I have Photo stream set on Cloud on both iMac and iPhone. The photos on iPhone appear in iCloud stream.

Space on my iPhone is tight. in general the photos I want to keep on phone I sync to phone after I have reduced their size (roughly 72ppi). I don’t want full sized photos on phone - after that is I have save them in iPhoto

I’d like to import the photos that appear in the iCloud in iPhoto and then delete them from phone. But want to be sure that this doesn’t then delete them from iPhoto on iMac.

I’d rather import manually and delete manually. So, I’m in control. Can I simply select photos from photo stream in iPhoto, drag then to an album in iPhoto, and then delete from phone?

Thanks for help.