Camera roll and photo stream question

I understand how photo stream works however I am wanting to check something.

On my mac I have events in iPhoto showing my photo stream for the past few months, am I safe to delete photos from my camera roll once they are in the photo stream on my mac? Am I correct in thinking that once there on my mac in iPhoto they are not using iCloud and I can delete them from the phone and they will remain on my mac? Scared to delete anything from my camera roll at the min

 

Thanks