Here is a short guide on how to get started with working in Photoshop and hand-drawn animation.
Here is a template file with the video layer set and timeline at the correct frame rate – 12FPS in Photoshop CC
Here is a short guide on how to import your photoshop animations into After Effects.
Here is a short guide on how to export from After Effects.
How to loop keyframed animations easily in After Effects
To quickly remove all keyframes:
In this box where it say MEL type this: cutKey -cl;