NDES, SCEP, Certificate Authority - change target CA

We configured NDES web server with specific issuing certificate authority server, after install the setting can be found in registry

HKLM\software\microsoft\cryptography\MSCEP\CAInfo

I want to change my target CA. So I changed the hostname and CN.

Is there anything else I need to do? Restart of service on the NDES?

or Will the changes take affect immediately?

Also, can I mix OS versions, like the NDES is WS2008 and CA server is WS2012.