It's good to see that the site is back up and running.
It would be nice to see some kind of system, perhaps similar to polier.ch, but perhaps a little less costly.
I am not sure what the monetary value of a photo is, but sites with photos prior to 1990 definitely have some kind of value.
Maybe 1 - 2 CHF for a medium resolution photo and 2 - 3 for a high resolution copy?
I guess you then have to come up with a licensing scheme. I don't know about watermarking, but definitely putting the name on the edge of the photo would be a good idea.