sp, I don't really understand your question, but I'll try anyway.
I don't think there's much that can really be done to allay the fears of immigrants (or immigrant-descendants who people seem to lump in the same category for some reason). Things like racism or homophobia aren't really affected by legislation or govt. action, they're affected by social change, like the kind we've progressively seen over the past decade or so.
All that can really be done from the perspective of the authorities/govt. I think sounds like it's being done - the authorities are attempting to find those responsible for racist attacks and enact the laws regarding it, while condemning them.
Is that what you're asking?
Also, could this be one of the reasons why black and Asian families choose to live in certain areas - 'safety in numbers'?
Potentially part of it, I suppose, but I think the main thing is that people just tend to like to have a community 'support base', if you see what I mean. Not because they just want to interact with members of their own community, but because it's just nice to be able to do so. I think people interpret this as failure to integrate but that's a rather simplistic reading of it.