When a user attempts to connect to a WLC
guest access SSID, does the web login page open up automatically?
Also is the web login page "https" secure rather than "http" clear text
As long as the WLC can resolve the users home page, which is not an intranet site or https, then the user will get a certificate error page first in which he or she will have to accept. Then he or she will get the webauth page. To eliminate the certificate error page, you need to install a 3rd party certificate, one that is standard on the device trusted certificate store.
User have to open web browser. It is HTTPS sesion.