The answer to your first question is definitely yes. Only when I become really friendly will I open up about it. I definitely have friends I meet in networking who are right wingers and who I eventually get to know well enough to tell, and they always laugh their asses off, and it's not a problem between us. But for a specific instance I recently had a woman referred to me by a IT guy I work with and she was right wing teaparty type, and man did she want everyone to know it. Do I think she would have bought her copier from me if she found out my politics? Absolutely not, she hates democrats never mind liberals and is very open about it.
The answer to your second question is no. The only time I have refused to do business with someone it was becasue they were a Hasidic Jew and refused to shake my hand. I went up to their booth at a tradeshow and this was a show I was at to actually do purchasing. He said he coudln't shake my hand. I was bewildered until I realized and I asked, could you shake my hand if I was a man? And he answered "of course"
Of course! Can you imagine? Of course if you were a man I could shake your hand because you'd be a human fucking being then! He saw I was upset and said, oh please don't be offended it's my religion. Well I am not a righty and I don't take this shit from Jews anymore than I would take it from a Muslim man who said the same shit to me, and I told him, well, misogyny is not a religion and if my hands are so dirty imagine how filthy my money must be.
And that was the only time. Unless a person was outright openly racist or sexist I really don't allow it to affect business. But not everyone is like me. And I know that.