Please do. The easiest way to upload an image is to use imgur.com, then copy and past the link and use the IMG button on here when you’re writing your post.
As for how long the bikes remain in the docks, TfL implied to me that they wait until there are enough to justify sending out a van. They wouldn’t tell me what ‘enough’ is. And it may be ‘enough’ in a particular neighbourhood, rather than a single docking station. They said they don’t have targets for how long a red-lighted bike should remain in a dock.