HI
1/ ok I think of a solution with development:
Copy at contact registration, the custom field "introduction" into the similar field under acymailing.
I have to make a similar request to a developer for custom fields in articles.
I regret that there is no integration of com_contact custom fields as you can do for your own fields.
I asked several years ago :-(
2/ok difficult too :-(
Maybe differentiated content (selling from 1/) would be a feature to not be classified as a newsletter?
*** Another suggestion: can you increase the session time? as I don't save anything in the browser and logging in to lots of sites is embarrassing.