What rail pass to buy 8-day holiday?

We (3 adults) will be arriving at Kansai Int. Airport (KIX) on Saturday, 1 Dec 2012. Details of our itenary will be as follows :
Day 1 : KIX to Kyoto; Kyoto to Osaka (hotel).
Day 2 : Osaka to Kyoto; Kyoto to Osaka (hotel).
Day 3 : Osaka to Kyoto; Kyoto to Kuwana (night light up call Nabana no Sato's winter illumination) to Kyoto (hotel).
Day 4 : Kyoto to Arashiyama & surroundings to Kyoto (hotel).
Day 5 : Kyoto to Amanohashidate to Kinosakionsen (hotel).
Day 6 : Kinosakionsen to Okayama to Kobe (hotel).
Day 7 :Kobe to Watayama (hotel).
Day 8 : Watayama to KIX.

My questions are as follows :
a) What type of rail passes do you recommemd to buy for the entire 8 days?
b) Can I buy the rail passes at KIX with credit card (Visa or Mastercard)?
c) Is there a departure tax at KIX? If yes, what is the amount?

Thanks a lot for your help.

What type of rail passes do you recommemd to buy for the entire 8 days?

A JR West Kansai Wide Pass is perfect for the last four days of your stay:
http://www.japan-guide.com/e/e2361_08.html

Depending on where your hotel is located in Osaka, I would use a Icoca&Haruka package or simply an Icoca prepaid card for the other four days. On particularly busy days, you could consider a day pass for the Osaka subways or Kyoto buses.

For the side trip to Nabana no Sato, I would use regular shinkansen tickets. Somewhat cheaper could be making the side trip from Osaka by Kintetsu limited express trains.

b) Can I buy the rail passes at KIX with credit card (Visa or Mastercard)?

Yes, I think so. Note that some passes are not available for sale inside Japan.

Is there a departure tax at KIX? If yes, what is the amount?

Yes, it is included in the ticket price.