With Cert Services 2008 r2 are we able to manage the Exchange certificates for CAS/owa and all other certs? If so can you advise how to set this up please? thanks

yes you can, but it is not so straightforward :-) why not using public paid certificates for exchange? ondrej.

Would it be better to use public paid for Exchange and not to use cert services for managing the exchange certs? Thanks

If you are planning to provide Exchange services outside of your network it is recommended to buy a certificate from globally trusted issuer, because you will not need to manage your Root CA certificate on unmanaged clients.http://en-us.sysadmins.lv PowerShell PKI module: http://pspki.codeplex.com/