Hijaab and Niqaab

Calling a woman wearing the niqaab a "ninja"

Q: If someone (Muslim) calls a niqabi a "ninja" (not in a derogatory way or to mock niqab, nor to make fun of the person for wearing niqab), will it be kufr? 

What if the niqabi didn't think much of it and just passed it over as a joke, because she believes that the person was just joking and not trying to degrade her or something. 

Basically, a ninja can be considered good or bad, but it depends on what the ninja does (apparently).

Wearing the niqaab even though one's family may disagree

Q: I just applied for a part-time job and they require that I remove my pardah (niqaab). I usually do not wear it in my home town due to my home situation as a revert and my family is against it and out of respect for them I do not wear it. However I made the intention to wear it full time even though my family would still disagree. 

My question is: What is the ruling on this and would it be advisable to wear it even though it may cause arguing and tension at home, and should I ever take off my niqaab (in future) for the sake of a job?

Woman going into her backyard without a scarf

Q: When I go outside to my back garden to throw something in the trashbin or do quick task, sometimes I don’t wear a headscarf or I wear it loosely. It can be inconvenient to have to put on proper hijab if I’m only going to go out for a few seconds. However, I usually peek out to see if the neighbours opposite our house have their lights on in their window and/or if they are actually looking out of the window at the time of me going to the garden. If I can see them then I will cover myself, otherwise I won’t. If a couple of strands of hair are visible then I don’t see it as an issue as they would not be able to see my hair all the way from their window. Is what I’m doing permissible?