In roughly reverse order:
All motoring offences (except certain parking contraventions which have been 'decriminalised' in some local authority areas) come under criminal law. So, by the strictest definition, even a simple speeding offence creates a 'criminal record'. However, the more commonly accepted definition of a criminal record (as used by the CRB) relates to convictions before a court (rather than to 'fixed penalty' offences). So, yes, your brother will acquire a 'criminal record'.
The Road Traffic (New Drivers) Act 1995 states that anyone who acquires 6 points during the first 2 years 'probationary period' will have their licence revoked. However, it's made clear that the 2 year period commences from the date that the person first passes their driving test, not from the date upon which they actually get a full licence. Therefore, your brother has completed the probationary period and it's the normal 12-points 'totting up' rule which applies to him, rather than the 6 points rule for new drivers.
http://www.opsi.gov.uk/acts/acts1995/Ukpga_199 50013_en_1
As you state, it's likely that your brother's insurance will have been invalidated but either the CPS haven't noticed this or, more likely, that they don't think that it's in the public interest to prosecute him for this. It's unlikely that any additional charge would now follow, although some magistrates occasionally invite the police and CPS to investigate matters which they seem to have ignored.
As you state, the maximum number of points which can be given for 'otherwise than in accordance' is 6. So your brother can't be banned from driving (unless, of course, the CPS take the unlikely step of adding an additional charge relating to 'no insurance').
Your brother now needs to retake both parts of the test and exchange his