Follow up to certificate sharing question
When you backup and restore a certificate for the purpose of moving the certificate you shouldn't have to include any clause related to the private key. I explained in the linked post the reasoning why the value of private key derives primarily from it's uniqueness and any operation that duplicates a private key dillutes its value: 


it can no longer be used as proof of identiy (ie. signature) since multiple copies exists throughout the world and non-repudiation is busted
it can no loger be used as a secure means to achieve privacy (ie. encrypt with corresponding public key) because since multiple copies exists, a copy may had been compromised 


Just to drive the point home, a certificate is a 'an electronic document which uses a digital signature to bind a public key with an identity' and the correct terminology is public key certificate. In other words a certificate does not have a private key. I myself am carefull to say 'certificate and the associated private key'.

The few operations when is acceptable to backup and restore a certificate and the associated private key are key escrow  and backup for recovery purpose (not for move).

Now after this long dissertation, the answers:


yes, use BACKUP CERTIFICATE testcert TO FILE = 'd:\mssql\testcert.cer'
Use CREATE CERTIFICATE testcert2 FROM FILE = 'd:\mssql\testcert.cer'