Originally Posted by Ovidiu
Lets assume the above scenario works, what/which SSL certificate do I then use for securing emails and FTP? Can I additionally create a wildcard/multi-domain certificate from startssl that covers all hosted domains so it can be shared for this purpose?
The CA (StartSSL, Comodo, GeoTrust, etc.) doesn't matter.
If you want to use a multi-domain (SAN) certificate, make sure to use the same key for all those websites.