Is pencil lead okay or will it leave acid on the page or photo? What about the eraser used to erase the marks?
Pencil marking should be fine in scrapbooking. It has been used by professional conservators for years. As for erasers, I would use the white plastic type (either polypropylene or PVC its OK here!) rather than a rubber one (like the pink ones on a pencil). Rubber contains many compounds harmful to photos.
