Hello Ben & welcome.
All of those codes relate to "Heated O2 sensor 2". You can see a full list of the codes here: http://www.350z-uk.com/topic/81962-350z-fault-codes-in-pdf/
When I had HFC's fitted on my Zed it did cause the EML to come on because it effected the O2 sensors nothing to do with the Cats deteriorating it's just that it messes with the O2 readings. Not a big deal.
To rectify it you/he will either need to remove the HFC's and go back to standard Cats, ...or have the EML turned off via a remap (UpRev), ...or you could try some O2 spacers (although they are not always effective), ...or as some do you could just live with it although I'm against that as then it could mask other faults as the EML would be on constantly.
Before buying the car though I'd want to double check that those are the codes read.