You can add new users with LDAP. Plus you can switch the update local behavior to only update when the user is created which would take care of your students adding emails. Also, once you have it going, you can set it up where any change in moodle is saved in ldap.
Anyway, I guess if you continue to have trouble with the plugin you are using, you might check with the developer. I can see that it has a few extra features but everything you have mentioned is already in the original plugin.