How to create a journey audience segment, use that segment to determine email dynamic content, and report on that segment in the send logs reporting?

I am new to Adobe Journey Optimizer. However I am well acquainted with Adobe Campaign Classic. 

In Adobe Campaign Classic I could divide an audience into segments and then reference those segments as variables to create dynamic within an email. I could also pass that segment name/ID to the email reporting logs. The advantage of this is that I could create a 1:N relationship i.e. one email but report at the segment level. This avoided having to create multiple emails. 

How can I create the same with AJO?

Note: the business has decided against using Adobe Customer Journey Analytics. As a result they have created a custom action to capture email send logs that is position after the native AJO email activity. This will form part of the business's solution to feed this data into a external reporting solution.

I want to know how we can enhance this current solution to avoid creating multiple emails for reporting purposes. Therefore, how might I use a read audience in a journey, split that journey into defined segments using profile or event data attributes, and use these defined segments as contextual data to determine dynamic content, and pass these segment names/IDs to the custom action payload to be captured in the reporting?

Your ideas, guidance, and approach to this problem is much appreciated.