I don't have any stats, but I know what happened in California some years ago. My reading of the Hispanic reaction in AZ: the law was adopted as part of a strategy to excite the Anglos against Hispanics and any politician, who is in favor of the law, is in favor because he either hates Hispanics or because he wants to show his voters that he hates Hispanics. This, most definitely, was how this was covered in the Spanish-language media (both within the US and outside).
As a Jew, albeit non-practicing, I know, how I would react to a law banning the use of human baby blood in ritual food made of wheat. No matter what else a politician, who proposed this law, would do, I would never vote for him. Even if we were to coincide on all other matters ideological, I'd rather vote for a Commie. I find it qutie plausible that, at least, AZ Hispanics will react similarly. I might be wrong, but Republicans in California have bet on that once a long time ago, and are still paying.
Um no. In fact, many polls show that significantly more Hispanics approve of this law than voted for McCain in 08, so in terms of political fallout, don't expect anything dramatic. The people who think this is a racist law targeting Hispanics were all planning on voting for the Democrats anyway, so there's really no movement. Gallup polled this issue actually, and found that the only significant change between pre and post-AZ law voting intentions is that blacks got about 2 points more Republican.
What really pisses me off is that the Republicans continue to let this charade go on. They should be storming Downtown Phoenix, pointing out how the ridiculous levels of crime (highest kidnapping rate in the western hemisphere for god's sake) are all tied to the massive amount of illegal immigration that comes through the Pinal county Border. Instead they treat the law like some sort of poison that you shouldn't mention in polite company.
I guarantee you, that if you had an up-or-down vote on securing the Border of the United States with Mexico, Hispanics would support it.