Is there a way to keep these things on between photos?
You mean you set guides for photo A, and then have the same guide set-up for photo B?
As far as I know guides are always saved with the file you're using it with.
But maybe this would be a workaround (let's state that image A and B are both flat, one layer-images, but it should work for more complex images, too, just put them into a layer group to be able to move/delete them easier):
1. copy image A. This copies image plus guides.
2. In the copy, put in image B as a new layer.
3. Unlock image A (which would be background layer) and delete it.
Now you have image B with the same set of guides.
If you use a lot of guides for a file, this might come in handy. For a few guides it's quicker to just draw them anew.
PS: Theoretically, there's a chance you can just drag a whole set of guides across from one file to the other. I never tried it.