So much prejudice...
Classic wow is not like retail, you won't be falling over each other in LFG. Parties are formed by talking to people, if they don't speak English and you don't want to group with them then don't. If they get a bad reputation they simply will find themselves not playing with English speakers much.
And if servers can handle 1 faction rivalry who cares if there is another. And if they are just speaking Spanish they will be as tagged as the opposite faction for most intents and purposes.
What I expect is people will form friends with others and keep playing with the same people most of the time anyway ( :