adding users & domains through command line user change password?

Hi all,

This is for a brand new fresh install of IRM 0.99, Ubuntu 18.04.3, Mysql

Since I won't be installing SOGO/roundcube/nginx, I have a couple of questions

1 - can I add users & domains by command line, since Iredadmin wont be available.
2- how can users change out their own passwords in the future?
3- Do I still need a Letsencrypt cert?

Regards