It’s been over a year since I flashed my P310, so my memory is super spotty on this. I really should documented what I did better, but looking through my downloads from around then it looks like I either used UEFITool_0.21.5 or UEFITool_0.28.0 - I think the NE one would break stuff no matter what.
Followed this guide
And
I doubt this will be much help, but I can try to answer some of your questions. I remember it being a HUGE pain in the butt, but I think my heart burn was from the P310 simply not having it in the BIOS, I had to splice a P320 BIOS into it.
I’d imagine starting with a P330 is already easier.