1. To buy Okuhida Marugoto Value kippu at Centrair.
I guess the ticket written by you is meanet Mu Sky ticket. You will want to buy it at ticket vending machines of Central Japan International Airport Station.
http://www.meitetsu.co.jp/eng/airport-access/map.htmlAlthough I thought you would be able to purchase the Marugoto Kippu at Meitetsu Travel Plaza to be located near the ticket gate of the station, The office is unlikely to mean that business is by Meitetsu Kanko.
http://www.centrair.jp/service/1190145_1621.htmlTomorrow, I will ask on the phone what they are selling it. Could you wait for a reply from me?
I'll post in the next night their answers.
2. Okuhida in November
November 24 is a holiday in the calendar of Japan this year.
If you are planning to ride the Ropeway, you should prepare the clothes for the cold.
By that time, snow will have fallen mountains already.
3. To buy Okuhida Marugoto Value kippu at Nagoya.
Mu Sky Exp. from Centrair stops at Meitetsu Nagoya Station. Service center is located in the B1F of the station.
The exact location of the service center is the lower-left corner of the map below of Nagoya Station. In order for you to go there, it is necessary to exit the Minami Kaishusatu-guchi, then go to the left.
http://www.meitetsu.co.jp/train/station_info/line01/station/1201.htmlThe web link you wrote is the branch of Meitetsu Kanko, it is not the Nagoya Station service center. The web link you wrote is the branch of Meitetsu Kanko, it is not the Nagoya Station service center. Sure, it's possible to buy tickets for you in the branch, but it is located in the complicated place. It is located in the underground shopping center D1 below.
http://www.sunroad.org/guide4.html4. Child fee
Children of the ticket fee is 2,680 yen. Your child under 2 years is free of charge.
5. To Takayama from Centrair
High-speed bus is operated once per day, but your children will get tired to ride it. I recommend that you use the train.