I have no idea on the technical side. I will say that I was puzzled about how to find your galleries (full disclosure: I'm new to this game) until I floated the cursor over an image and tried clicking. My personal preference is to give more freedom to viewers to explore rather than guiding them on a linear tour through each gallery, in which case you could have a text block above the gallery; but if you're going to have visitors click through as you do, maybe a sort of generic-but-apropos first picture with text over it might be a possibility?