I don't know if "Spring 2011" was announced in an official press release but it does seem to be the official release date at the moment - if the game is released after June 20th I think it's fair to say that it's been delayed. However while this might frustrate a lot of people I bet most will accept a delay if they feel the game needs it.
I like to think the worst.
When it comes to games in developement that's generally the wisest course of action.
I doubt it, since they are already this far into beta, it seems odd to me that they would need artists to work on the game. Isn't most of the graphics and art done during alpha?
Good point, from my understanding when you enter beta all of the final art should be in place. Some things may need to be tweaked but it would be odd to put a whole bunch of new art in.