As I mentioned above, you are not really supposed to have access to all functions in NL.something, since it's not part of the open API. Maybe later we can provide some deeper insight into this for Python experts, but we don't have any such material to share right now. We can help with specific questions, however.
I didn't understand the question on molecules. You can open the Database from the Builder and click "+" to add the selected molecule to the Stash, and then use it from there to modify it, add it to other structures, etc.