Purdah

Keeping a non-mahram as a Facebook friend and conveying salaam to non-mahrams

Q: 

Can I keep a non mahram as a Facebook friend? If I don't talk with them unnecessarily & don't post any photo of mine? Will it be considered as zina for me? Can I give likes to the posts of non mahrams or will it be considered as zina? 

Can I give salam to my non mahram relatives? Will it be considered as zina?

Driving non-mahrams

Q: Where I'm working, I know the people quite well. I've been working here for about 3 years or so now. 

They give me duties to do, example, to take their mother or wife or sister to go shopping or to transport them from one place to another. 

I personally don't like doing that because they are non mahram. My wife gets angry with me when I do those things and she doesn't speak to me. 

If I do tell my boss that I can't do those duties, I know personally they will fire me or treat me differently although they are Muslims. What should I do?

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?