Anyone can buy a Carte Orange, and you don't really need a photo because no Metro official ever asks to see it (at least no one has ever asked for mine). However, my Carte Orange (which looks like a regular metro ticket except it's white and orange instead of green) is for a month; I'm not sure one-week CO's are available. I can check. In any case, carnets are a good deal: 93 euro cents per ride on one of the world's best subway systems can't be beat.

Bons voyages!

Evan in Paris