I am extremely new to AE. I have CS6 and am trying to learn it on my own... but it's very complicated.
I have a template I am working with that I want to insert video clips into. The template has jpegs that say "insert photo or video here". How do I swap the jpeg with the video clip without losing the keyframes and effects? I'm not well-versed enough to just re-do them all. I am using the templates to learn the program but to also build a few videos for the non-profit I work for.
Another thought I had was if it was possible to copy all the attributes/effects/keyframes from one media piece to another. So if I were to add the video clip to the composition and copy the attributes from the template photo to the video clip I just added and then make the template photo invisible. But I haven't been able to figure that out. :/
Welcome to the world of After Effects! As you've noticed, it can be pretty complicated. I highly recommend that you start here. That is a set of resources specifically curated to help people new to AE get started off on the right foot.
To your question, this page in the AE help has what you need. It says to select the layer you want to replace in the Timeline panel then Alt-drag (Windows) or Option-drag (Mac OS) your new footage item from the Project panel onto the selected layer in the Timeline panel.