Hola!
FOP 2.27 under https requires ssl certificates to be configured, the same certificates you use for your web server, by default the config is this:
ssl_certificate_file=/etc/pki/tls/certs/localhost.crt
ssl_certificate_key_file=/etc/pki/tls/private/localhost.key
If you have those files (/etc/pki/tls/certs/localhost.crt and /etc/pki/tls/private/localhost.key) you can uncomment/set those lines in fop2.cfg and then restart fop2.
(browsers should enforce a secure web socket connection when using ssl, firefox does that, chrome not yet, but it will in the future, so fop2 defaults to secure websockets if you connect via https).
Another option is to disable websockets in /var/www/html/fop2/js/presence.js , that way the old xmlsocket feature from adobe flash will be used instead, that works no matter the protocol, because of flash.
Regarding confbridge, fop2 supports it but asterisk only has confbridge manager support since version 11, not in version 10. You should install the meetme module in freepbx to get rid of that warning.