"Null" phenomenon and parthenogenesis are wholly unrelated and have nothing to do with one another.
No necessarily
Yes, it is. But it is not at all a subtle morph that could ever be mistaken for a WT
Obviously there are: Disco and Vanilla and RDR DesertLemon and Sulphur and Flame Hypo and Lucifer and Eraserhead and... But here is the thing, there is an absolute trend line these morphs follow and the more normal they look the less they react with Fire. So if that female is some type of "cryptic" BlkEL allele then she would not produce a white snake when bred to a Fire.
Fires and normals