Categories/images can be, theoretically, unlimited. The galllery will resize/reposition the elements according to the image dimension. The maximum size is set by the Stage dimensions. The gallery only works with image files (PNG, JPG, GIF). The package includes: small description file, source files (.fla, .as), source design (.psd), test folder with the file embed in html, with the gallery going in fullsize (just like in the preview).