RE: battle fronteir/ other post-game activities
I haven't reached the battle frontier in HG yet, but just from what I've read about the events it dosen't seem nearly as good as the Emerald one. Like many other said in this thread, Emerald had an AMAZING Battle Frontier, I beat all of them except the Pyramid. Kinda wish I didn't sell my copy of Emerald now :/ But I had some issues with the name and save file and would have had to start over anyways.
So I hope that whatever BW has is on par with Emerald's frontier. The Battle Subway does look good, but obviously we're gonna need more then that lol.
Also I hope they have something similar to the Pokeathalon with minigames where you win prizes, as an optional thing of course.