I'm not sure of a way to do that? I usually import/place all my elements on a slide that I want to be involved in advanced actions. Only after everything is placed will I begin building the actions. It usually takes quite a bit of planning, but is how I do it. I don't think if you delete the placeholder you're able to rename it the same as the image you're replacing. Plus, as soon as you delete an image that's part of the advanced action, the particular action changes to a continue if I'm not mistaken?
As far as mass changing a certain element to replace another across multiple advanced actions, I don't think that's possible. Most likely will require you going through and making each change as necessary.
