How to handle multiple associative tables?
Yes, if you want to reuse an image between multiple entities and a single entity can have multiple images you'll need to make it a many-to-many relationship. And yes, you would want to create multiple associative tables for each many-to-many relationship.

The only way around this would be to create one Entity table that all of the other tables pulled their IDs from, but I think what you currently have is easier to maintain going forward.