If you're very very good with find-and-replace -- AND if you back up your entire site before attempting this -- AND if your existing photo pages are consistent in all the code before and afer the photo/description part -- then you could possibly do a sitewide find-replace to replace all the non-template code with the template code. It would take at least two passes -- replace all the code before the photo/description bits, and all the code after them.
However, you should not do this unless you feel confident of your find/replace ability, and you should absolutely back up your site beforehand. You're been warned: if the whole things gets totally mucked up and you didn't back up first, you'll have only yourself to blame.
Provided you do a complete site backup first, there's no harm in trying it.
can you also take off a template from all the pages on your site in one swoop?
what happens to a site that wants to put all content into a newly formatted template? just saving the new template as the old one and then it will update all of them?
i guess that might work no?
also: my content, when i put a template around it, all gets put into one size font, even if i have it differently sized in the pre-template content, is there any way to avoid this changing of the font once you put the template around it?