Howdy,
No, It does not need anything special in the files. Of course good files are a good investment. Among commonly available: Vallorbe,(Swiss) or Pherd (German). Carlton brand are Pherd. Viahalla (fin) files would be next. Most off brands may be the Finish file. The country of origin stamp will give it away. The Finish file is quite OK. I'd avoid Oberg (Portugese) or Oregon. Nicholson died years ago in chainsaw files in my opinion, so USA files are out of consideration.
Yes, the Chrome plate is hard. In fact darn hard if they have maintained the quality control like we had on it when I was with the company. Since it has been take over by first Sandvik, then Snap-on, and now Oregon, I haven't a clue!
Regards,
Walt Galer