Eleven will air Supernatural season 5. From what I can see on the TV spot, Smallville will resume from season 8. I can only assume SGU will either start from the beginning or from where it was left off, which was like 4 or 5 episodes in. I can't locate any program schedule yet, but you'll know when we all know!
Any promo from Eleven is better than no promo. It's pretty ok but if you haven't seen Supernatural season 6, the trailer is pretty spoilery.
Here is an old promo Jensen and Jared did for Channel Ten a few years ago, probably in its first or second year on Channel Ten.
I'll be watching to support the shows!
Here is the loop on Eleven with various shows: