It sounds like what you want is a content management system and a photogallery. There are many to choose from for both things. For the content management system I would recommend, Joomla!, Xoops, or Postnuke to start with. All three are relatively easy to use and have loads of support information on their respective sites. For the photogallery, I'd recommend Gallery or Coppermine, both of which also have loads of support.