How can I delete a photo off my camera roll, but keep it in my album?
My workflow for this - not using iCloud - is:


import the photos into an app (I use Lightroom)
label photos I want to end up on my iPhone with "for-iphone"
export photos labelled "for-iphone" to a folder of your choice (I use "Pictures/for-iphone")
in iTunes turn on "Sync Photos" for your iPhone [note: find "Sync Photos" by plugging in your iPhone, opening iTunes, clicking on the little phone icon to the right of the "Music" dropdown, then clicking Photos in the list below]
at "Copy photos from:" pick "Choose folder..." and navigate to the "Pictures/for-iphone" folder or your equivalent
Hit Done


Your photos will be uploaded to your phone independent of the Camera Roll.

Each time you sync any newly-added photos in the for-iphone folder will be added to your phone.