How do we tie groups or memberships to a product and be able to mail with it?
One approach to this would be to use Relationships. Make a Relationship Type of "Editor of / Editor is" that will connect Individuals with Organisation sub-type "Magazine".

Use that relationship to connect John as the Editor of the Jungle Journal. And similarly to connect Bob as Editor of the Birds Books.

Then you can make a Smart Group of all Individuals that are 'Editor of'.

Then repeat for the other Relationship Types, ie make one for 'Author of' and another one for 'Reviewer of'