I am going to assume this would be custom JS but not sure if there is a simple solution.
Part 1: We would like an image to show, then on scroll be replaced with a different image. Both images are same size.
Part 2: We have a ‘Navigation Inline’ element that we would like to hide on scroll - reappear at top
Part 3: We have a ‘Navigation Dropdown’ element we would like to show on scroll - disappear at top
We found a help topic here that showed us how to replace the background color and that worked great. These 3 options though, we have yet to find a solution.