You can use this theme component to see the available plugin outlets (except the ones in raw templates):
There is no specific documentation at the moment. You can read the source code to understand the context. The component gives you a link to the source code. You can always ask dev if you don’t understand something.
The posters from the topic lists can be found in these raw templates:
Depending on your precise needs, you may need to overwrite the posters-column raw template (which is not recommended). What are you trying to achieve here?