As for dragons and stuff...
Brandon Snow, King Torrhen Stark's bastard brother, wanted to kill Aegon's dragon. I think he's the one that Bran sees in his weirwood vision carving 3 weirwood arrows. They went south with an army, and Torrhen ended up changing his mind and sent 3 maesters with Brandon Snow to treat with Aegon.
I think he went south with an army in order to lure all 3 dragons, but only Aegon showed up with Balerion. They couldn't kill just 1 dragon because that would not only piss off Aegon, but his sisters would be much more careful in protecting their dragons and Brandon may not even get a chance to kill them.
Another thing, there's an illustration of a few pages of the new World of Ice and Fire that's due in October (You can pre-order it on amazon). You can look at them here
There's a page on the Faith Militant Uprising and this caught my eye: "A rainstorm dampened Balerion's fire but could not quench them entirely."
This makes me wonder how effective Dany's dragons would be in a snow storm like that one we see in Winterfell in adwd.