1) Is greylisting effective any more ?
Greylisting is effective against any attacker using a simple spam script or mailer utility. Greylisting is essentially ineffective against a legitimate mail server. It seems the recent trend in SnowShoe spam is to purchase a hosting package containing a new domain, valid PTR, SPF, and DKIM records. Greylisting is essentially useless to these types of attacks.
So to answer the question, Greylisting is effective for certain types of attacks. But not so much against the scenario mentioned above.
2) Is there a way to see an SMTP report of emails that were greylisted and only ever attempted once ?
At this time this is not possible, you would need to manually review the SMTP logs to determine this information.
Technical Support Specialist / Internal IT