You can call /api/v1/users/${userId}/roles to list the admin roles for a user.
An SSWS API key cannot be generated via an API call, you must generate it in the UI (while logged in as the admin user in question, of course).
If you need something more programmatic, you may want to considering using OAuth to authorize the calls to Okta instead. More details here: Implement OAuth for Okta | Okta Developer and Implement OAuth for Okta with a service app | Okta Developer