Ok, I was woken up in the middle of the night to post this hot off the presses summary/ answer to questions. Any omissions are purely due to my sleep addled brain :b
1) Does the Baratheon name come from Orys, or did he take up the name from the Storm Kings?
Ro informed me that the Baratheon name has always been there (not sure that is an answer, but it's the one I got)
3) Catelyn recalls that at Riverrun, Brandon told her that he would return soon for their wedding. Where was he going?GRRM refused to answer where Brandon was going.
4) What happened to the last King of Mountain and Vale?Nothing happened to them, they continue to be the lords of Arryn.
6) When, specifically, did Benjen join the NW? Was it a couple of years after Ned returned, or immediately?
It was within a few months of Ned's returning. The reason being that there always was a Stark at Winterfell, so he had to stay there until Ned returned. GRRM refused to say the reason why Benjen had to join the NW.
Now as to the questions of which POV's show up in which book, the following will show up in AFFC:
Jamie, [Note: Spoiler POV redacted], Arya, Sansa, Sam (Jon will be in the first Sam chapter), the Iron Isles, Dorne, mystery POV (we don't know who the mystery POV is yet!). Asha will be in AFFC, in fact, all the chapters in Arms of the Kraken will show up in AFFC.
The following will show up in ADwD:
Arya, Bran, Jon, Dany, Tyrion, and Asha (she will be in both books, as she gets involved in affairs of the North)
Other tidbits: [Note: Spoiler POV redacted] has the most number of chapters in AFFC, while Dany has the most in ADwD. Also, the number of Tyrion chapters is going up from 4 to 7 in ADwD (his storyline is basically beinbg expanded).
[Note: Next is a clarification from a later post.]
Davos is in ADwD, according to Pod and Ro from last night. Also, I didn't mean to imply that Benjen "had to " join the NW. We don't know because GRRM wouldn't elaborate on the reasons for Benjen joining the NW.