I am making a slide show in after effects and was wondering how to make it into a looping template that involves photos that I can edit in a way that allows me to switch the photos out. If there's a different way to allow photos to be easily switched in a loop that doesn't require a template format, that would work as well.
The sole governing thing that defines a "loop" is the composition duration or for that matter whatever duration you set for the output clip when rendering. The rest has nothing to do with AE. Looping is handled by whatever player software you use. Everything else is basic AE stuff like replacing the footage in the project window or timeline. You may want to read the online help on these basics.