regarding the SSL I think I found a solution by obtaining a certificate from starssl and put it in my main Apache Server (that one that is connected to the internet) and configure the SSL connection between the apache server and the KVM MIAB NGINX server with the following config:
ServerName box.maderthaner.net
ProxyRequests On
SSLProxyEngine On
SSLProxyEngine on
SSLProxyVerify none
SSLProxyCheckPeerCN off
SSLProxyCheckPeerName off
SSLProxyCheckPeerExpire off
ProxyPass / https://192.168.122.99/
ProxyPassReverse / https://192.168.122.99/
SSLEngine on
SSLCertificateFile /etc/myssl/box.maderthaner.net/2_box.maderthaner.net.crt
SSLCertificateKeyFile /etc/myssl/box.maderthaner.net/private.key