I'd also like to think of The Omen as a b-sides collection of sorts. I'm guessing Welcome Oblivion is a concept album, and the songs on the EP were parts they thought could survive as standalone tracks worthy enough to release in an effort to hold fans over until the full album comes out. The subject matter in 'Speaking In Tongues' seems to imply that there's a bigger picture that hasn't been revealed yet (dissapointed that it likely didn't make the album)
Of course, even the word 'omen' implies that the EP is only a small sample of bigger, hopefully better, things to come.