Well some states did have laws that said the nominee must be named by a certain date which happened to be before the Republican Convention, but that's all pretty irrelevant anyway.

And the Republicans hate Hillary for the same reason they hate Bill: they have amazing political skills and present a very tough challenge. The Republican Party doesn't hate people like John Kerry because he was eminently beatable. In general, the more strongly negatively the other party reacts to a candidate, the better that candidate is.