So how is saying you don't want to live next door to someone discriminating against them? How is not living with someone ill treatment?
If their race is the reason you don't want to live next door to them then that is racist. You are assuming all the rest, culture, lifestyle, whatever based on their race, not because you met them and actually know.
It isn't discrimination though. It is only discrimination, from a legal standpoint, if the situation is reversed, i.e. you prohibit people of a certain race, or who are not of your race, from owning property in your neighbourhood. Ethically it would also be pretty bad if you were to treat them like crap to try and make them move away.
How is not wanting to live with someone any indication of the 'character' of any individual? There are cultural lifestyle differences between people.
It depends on the reasons for not wanting to live with someone. If it is because of race or nationality then that reflects pretty badly on a persons character IMO. To me even cultural differences as a reason is pretty bigoted. If it is because they inconsiderate or are generally a pain in the ass then fine. It is true there can be connections, e.g. cultural and lifestyle differences may RESULT in people doing things that annoy the shit out of you, but you can't go generalising such things to EVERYONE of a certain ethnicity, nationality, culture, whatever.
In the example you gave a black person can move into a neighborhood and their neighbors are also free to move. I don't see why this is an issue of racism. If they dislike the way they are treated by their neighbors then why would they bother moving in?
People segregate themselves all the time, especially in the States.
The way this is phrased everything is fine IMO. People can self-segregate themselves all they like for all I care, so long as that doesn't make them intolerant or unwelcoming towards others who may wish to join their community, so long as the joiner isn't going to make themselves a hassle.
There is a slightly side issue that one might raise if one decides to take what I have said to the extreme, that being a totally homogeneous future in which all cultures and races have been bred into a kind of average human. This I think would be sad, since it represents a loss of culture and diversity, so I believe protection of such things is important. Therefore governments may have to regulate immigration etc to preserve their own cultures. This I think is a seperate issue though, I think we are more concerned with things at personal level here.