Really cool xml photogallery with hidden thumbs...i need some xml help

Hi Guys i bought this gallery online and it looks really cool but i am trying to add some more to it but is not easy.

  1. i would like to add a next and prev function to the xml gallery, buttons that can advance the images just by clicking left or right with the mouse
  2. I’d like to add a caption text that stay still(the one that is there moves on rollover action and is added to each thumbnails but i deleted them) and that will show the caption everytime i press a thumb, basically an info text box that communicate with the xml.
    Thank You show much i’ll add the zip with the files.