Sending emails via API

I have a potential customer who has a few questions about the API:

  1. Where would the email sent stats be reported? Do you have a demo we could check as to how this would look like? Does the above send email function automatically create a “email record” for each contact (Keap REST API) ?

  2. Lastly, is the only way to segment your contacts to use tags and then pass each of these contact ids one by one when we send an email? Is there no way to create “contact lists” in your system to simplify this process and have lists independent from tags?
    (for context - this is what they have already been sent -
    The email endpoint allows a message to be scheduled directly; you can specify a list of contact IDs which you can obtain from the endpoint Keap REST API if segmenting by tags (which is typical). The scheduling would need to be done on the sending system rather than on our end. )