Q: "Over capacity": How can I delete photos from iPhone / set the maximum capacity of iCloud photos to be downloaded to iPhone?

Hi,

My iPhone regularily goes over capacity because it stores, or tries to store, too many photos/videos from iCloud on the device.

How can I delete photos from the iPhone (but not generally from iCloud/Photostream). How can set the maximum capacity of iCloud photos to be downloaded to iPhone? (I am searching for a setting like "keep the last 2GB of photos/videos from iCloud/Photostream, but not more than that. I know how to turn iCloud off in total, but that is not what I would prefer to do, I just would like to set reasonable maximum.)

Thank you for your ideas!

Generally, I someone could point me to a good tutorial on how local photos vs. iCloud photos vs. Photostream are supposed to work that would be great as well, because I have many other problem with Apple's system in that regard as well (esp., despite that obviously a lot of space is taken up by photos/videos on my device, my iPhone still downloads recent photos/videos over 3G... I also have the problem that all photos appear double if I try to copy to my Mac with ImageCapture or iPhoto, but there is only a single copy (no HDR, burst or the like) when seen with the Photos.app of the iPhone itself... I came to believe that Apple's photo system is somewhere between counterintuitive and plainly not working... (/rant off) )