Hi @vish,
The short answer to A is that empirically it doesn't prove to be particularly beneficial for most cases and NER and tagger are already looking at the same features i.e tok2vec layer.
Here's a thread that discusses similar questions: Does spacy NER model use POS for modelling
Also see this thread on spaCy forum on how to use POS as annotating component for NER if you would like to experiment.