Akita - Nyuto Onsen

hi! i''ll be in tokyo in December and plan to get the tohoku pass. here are my questions:
-is there already a lot of snow in akita by 2nd-3rd wk of december?
-Taenoyu or Ganiba?
-where to book taenoyu? ganiba is on japanican, is this site reliable?
-are the open bath onsen open 24/7? or do they close at night?
-any other onsen villages you can recommend? preferably those with open baths

I can't answer most of your questions, unfortunatly, but as no-one has replied yet I figured I'd at least give a reply to your last question.

I've stayed at Tsurunoyu Onsen (the old rooms) and really enjoyed my stay there. There are beautiful open baths (a mixed and a female-only one, there wasn't a male-only outdoor bath). And there, at least, the baths are open all day/night for overnight guests but not for daytrippers.
I used Japanese Guest Houses for my booking and it worked splendidly. From what I can see, Japanican looks good, but I've no experiences with it myself.

As for booking taenoyu... well, I did find this site: http://www.taenoyu.com/ and there's an e-mail adress and phone number at the top of the page that you might try? If you click the second link (next to 'top') you come to some sort of booking form with dates - I've succesfully managed to book a ryokan with a similar form and a little help from Google translate, but that might be a bit too much of a gamble for some.