It doesn't let the audio clip/exceed safe volumes and always applies some sort of a limiter, even if it's disabled everywhere in the settings. Try using an EQ on a bass-heavy track and see that it's limited.
Try jumping back multiple times in a song at its beginning, and it will play in lower pitch.
Compared to what? Such a statement is meaningless without comparison.
https://github.com/clsid2/mpc-hc
In many ways it's a display wrapper about codec components, the display part is in active maintainance and bug fix mode (last update two weeks ago) and the codecs are constantly being improved (and expanded as new ones emerge).
There are two or three MPC-HC spin offs that are tweaking the core to do new things.
can you please explain what you mean with this acronym?
EDIT: this seems to correspond to https://en.wikipedia.org/wiki/MPlayer