Ok so here goes. I'm not a fan of Google and would much rather have Windows 10 Mobile on my Samsung Note 4. I am aware that there is a custom ROM for Xiaomi M14 devices. Would this work on the Samsung Note 4? And if so how do I flash the Samsung with it? Any indication on my options, would be greatly appreciated.
If you find a special custom ROM for your Samsung Note 4, then it could work. Otherwise it will most definitely not work. Besides flashing unsupported ROMs is normally accompanied with lots of beta testing. If you are not a developer or have an active community where you can report errors you encounter, you will most likely end up with errors which will greatly diminish your users experience and which will not get fixed. As far as I know, Samsung sells different models under the brand "Note 4", so that makes getting the right custom ROM even harder.
Regarding Xiaomi Mi4 http://www.windowscentral.com/microsoft-making-custom-rom-allows-android-smartphones-run-windows-10-phones , it is Microsoft itself, that is porting the system, hence one can expect errors to be corrected over time.