1) Turn on Red October JRVR as your video mode. You can just leave all the settings as default and unless you plug into an 8K display, no scaling should occur.
For audio, since you likely want DTS-HD MA, ATMOS, etc without changes, you want to turn on bitstreaming for audio over HDMI.
In MC, click Player at the top, then Playback Options. For JRVR, click the Video tab. Video Mode drop down, Red October JRVR. Hardware accelerate video decoding when possible for best performance. This does not modify the stream, just uses graphic hardware to do the heavy lifting.
In the same menu, go to the Audio tab, under Settings you will see Bitstreaming. Choose HDMI.
This should get you HDR 10 and advanced audio formats without any molestation.
If you want Dolby Vision, well you are pretty much out of luck. JRVR does a good job faking it but cannot pass DV directly without doing something magical to it, so that won't fall into your "unaltered" bucket. MC will use the HDR10 portion of DV though so you can still get some kind of HDR from them.
2) No idea.
3) Can't help on that one either, sorry.
