Dark frame subtraction and WB question

I think that I am doing my dark frame subtraction correctly but am having trouble with a couple of details.

I am subtracting the dark frame from the exposure, dark frame color profile and white balance set to match image. Dark frame ISO, exposure same as image.

This removes the amp glow but leaves the image with a greenish cast. Is this normal?

Is it caused by removing all this magenta from the image and is the proper way to correct for this by white balancing on a known point in the post dark frame subtracted image, or is there another way?

Probably silly question but why is the amp glow magenta? Since that presumably isn't affected by the CFA, is magenta the color you would end up with combining an RGGB block of pixels?

Thanks for any tips and or suggestions.