Yea, you will need error canceller to stop the flickering and error code.
I too hv lux AE halogen
4300k will be pretty much white with bit of yellow. Correct, 4300k bulbs got that brown rod and some higher Kelvin comes in different color rod like white or blue. Best thing for u to check s put yr 5000k bulb on a piece of white paper, it should show a hint of blue on the bulb if is really 5000k.
Is not going to be exact match to the Lux due to hid brand and in different housings (fogs). Do keep in mind seeing it live in person vs camera pix is quite different too.