ED, I don't know what it's worth, but from your requirements, http://piwigo.org/ seems to be a viable option.
I can't say I've used it, but I'm going to switch from my old - and not fitted to my needs - gallery engine, to this engine soon.
I can't say I've used it, but I'm going to switch from my old - and not fitted to my needs - gallery engine, to this engine soon.