Songs About an Angel soon? Hell yes.
In Circles and Seven are already in steady rotation. So will the whole album be released in track order then?
among dreams we're best friends/while in life we float apart
their website, including Song About an Angel. Rhythm Authors also does, and some other authors may as well. In addition, many authors have threads in these forums listing what they have in the pipeline.
Also, if you know the author to a particular song, you can search for them on creators.rockband.com. You can't access the pages for songs that aren't approved yet unless your creators account is tied to an XNA account (which costs money), but with just a creators account (which is free on its own), you can still see songs that are in playtest and peer review on an author's page, so if you search for an author you'll be able to see what songs they're working on. You won't be able to see songs that are between revisions or in quarantine this way, though, and sometimes record labels or bands will submit songs to peer review through their own account instead of through the author's (for example, to find the Asking Alexandria song you have to look up Sumerian Records' account, not Rhythm Authors' account). So it's not reliable, but this can be a way to check on songs that you know the author for.
Aside from these methods, you just have to scour these forums for announcements or wait until things are released, as Fairwood says.
Why the fark is that O Come O Come Emmanuel song listed as new again?
They need to quit letting crap into the store if it is not the final product if they can't figure out some way of just allowing a download of the new one for free...not in addition to the old one but in replacement of.