Hi kdj,
I can't recall exactly if the key is by the cat, but here are directions:
Exit the shed. Cross the wooden bridge. Turn right at end of bridge and immediately turn right to look under the bridge. Go forward and pick up a brown thing in the water - room 18 key.
Yes, the photos are developed in the booth at the plinko place.
If you're not getting the call from Logan, there's something you've missed doing to trigger it -- check your task list to see what's outstanding.
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"Bleat, Watson -- unmitigated bleat!" ~ Sherlock Holmes