We have a drafted implementation of SAML for 1.8 which should allow all of the above. It is being tested at the moment.
CMS Code: https://github.com/xibosignage/xibo-cms/tree/feature/saml
Manual: https://github.com/dasgarner/xibo-manual/blob/develop/source/en/users_saml.md
Feature: Xibo SAML Service Provider
I believe that SAML will allow for Shibboleth, although admit to not being an expert in the area. Comments welcome.