As far I as recall none that you have mentioned were ever enabled/activated in the game. Why would you be interested in collecting useless sailors anyway?

For your hobby I suppose you could start collecting low base stat sailors. Or maybe just classed on time sailors who should have been delay classed for the most benefit such as IJN DP and UK AA, etc. Maybe start a Medic collection, or Restorer's from every nation.

Are you sure they were NEVER in game ?

Hm...as for collection, I only collect hero sailors and EBB/ECV.

MN machine gunners anyone?

um, they were in game.  Early early beta.  I've seen an accountant at some point.  Word on the street is there are a few drill trainers floating around.  Epic expert gain when they are on a ship, or some I am told.  :p

I had each of these guys and NF reset them on me years ago.

Lol they were active. I don't know of Ground crew. But I had an accountant. Helps you get more credits during battles. 

The accountant would have been great. Imagine - all pool your money together in the big fleets for the 10% interest :).
I always wondered as well as they wasnt in EU server too. Intriguging concept - that clearly could not ever have worked (the accountant 'sailor' i mean)