having every domain use the same SSL certificate on a PSA server?
Yes, as long as all of the domains are using name-based hosting and the same IP. All of the domains can use the same certificate; however, since the domain names are different, the certificate will not match all domains but can still be used. This certificate is located in the /usr/local/psa/apache/conf/httpd.pem for standard installations and /etc/httpd/conf/httpd.pem in the rpm install.