- Have the same password for the protected images and set up so that it only has to be entered once by those trying to access the protected photos for the first protected photo they want to access, not individually for each protected image
You can't do this. Visitors will have to enter the password individually for each image.
(this is the bit that's got me stumped)
At the moment I have duplicate galleries, one in a public group without the selected photos and the master gallery with all photos in a password protected group. The plan I'm on means I'm not concerned over space, but having two galleries with the same stuff seems wasteful and complicates maintaining it so if there's a way I can achieve the access control I want then I'd like to change to this.
Here's the solution that requires the least amount of work:
Create a private gallery and put all of your pictures in it. Even though the gallery is private, you need to mark all of the pictures as public.
Create a public group with 2 collections inside of it. One collection is public and one is password protected. Put each image into the appropriate collection. All visitors will be able to get into the public collection. Only visitors who have the password can get into the second collection, but all images will be visible once inside.
Any updates you do to images in the main private gallery of originals will automatically be reflected in the collections.