Can't answer your first question.
The 2017 contributions may not be complete yet, which might explain the 39 contributions instead of 52.
Work Jan/Feb - let's say 8 weekly PRSI contributions were made. Employer hasn't submitted 2017 returns yet, so they're not on the record.
If the record was compiled at end November, then there are 4 or 5 weeks in December that haven't been counted yet.
The remaining 39 have been credited because the person is on a DEASP payment of some type, I'm guessing?