Responses are not meant as a substitute for professional advice. Answers are intended as outline only the advice of a qualified professional with access to all relevant information should be sought before acting on any response given.
Personally I always tell clients that the end of month rule still applies as they very often try to push it over month end but yes, deadline is the 7th following the month end after the period ended.
I registered voluntarily for VAT as all my clients are VAT registered except one and you do returns etc in exactly the same way as you would for a company that has to register. Once they are reigstered there is no difference whatsoever.
Whether he was correct in registering depends on a few things as Tim says above. Has he told you why he registered?