Multiple reports that at least some of the pipes contained an explosive powder. None went off, which most likely means a poor design (though there's a chance that's what the bomber wanted). But presence of explosive material means a real bomb. 1/2
Re: Waters, you're asking why send her two and other people one, yes? I don't know. Almost certainly too quick for a copycat. One intercepted in Maryland the other in LA. Could mean more than one person in on the plot. Could be a mistake. Could be coincidental. Need more info 2/2