[drc]

The photographer does matter, but the photographer is rarely listed on a news photo so it usually doesn't matter. If the listed photographer is very famous, add a premium. If the photographer isn't listed or isn't very famous, don't worry about it.

The stamps and captions are important in that they help establish age and originality, especially for lay people. I prefer a good stamp or identifying tag on the back of a photo, whether it's from a newspaper or Vogue magazine. It's easier to resell a photo that has such identification on back, especially if the claim is it's by a famous photographer ... Many wirephotos have the caption on the front, so obviously in those instances an additional stamp or tag on back isn't required.

Image subject (ala Babe Ruth, famous particular game) is important along with quality of the image (clarity, artistry, uniqueness, even humor).

As far as condition goes, look at overall presentation value, in particular of the image. A wrinkle or crease to the white border pretty much means nothing, though a crease through the image would. Some honest wear that doesn't effect the image might not lower the value. With a vintage photo, grade Ex should be worth about the same as grade Near Mint. No one should care that an edge isn't Gem Mint. Realize that baseball card grades are applied to cards were thousands to tends of thousands of a card were made. With that 1909 Ty Cobb, there will be no more than a few in existence. Worry about overall presentation value, not razor sharpness of edges and corners.

Besides, you won't find Pre-WWI news photos that are Gem Mint. If you find one, its probably either a reprint or was trimmed. News photos were production items literally paper thin, and didn't last to today in Gem Mint condition. Dings and toning and wrinkles are the norm.