Daddy Kuma

It’s propietary

To me, one of the best players for windows along with foobar2000

I used, but today I use Clementine (is still alive) and sometimes QMMP with some winamp skin

VLC It’s a good Music player if you only need to play music

I Think so.

Yep, but if it only he need to remux then is less time than reencoding.

You can convertí the files in another playable format with Handbrake, probably you Won’t need Change the codecs of the files only the container and the conversión will be fast than reencoding all