5-day trip - Is JR pass advisable?

Hi. We (2adults, 1 teenager , 1 -5yo girl) are arriving at KIX airport on Feb. 12/2015 at 8PM.

Our proposed itineraries are:

Feb12 -arrival at KIX Airport at 8PM
Travel straight by train to a hotel in Kyoto Feb 13 - Explore Kyoto
Feb 14 - Snow experience at Biwako Valley Snow Resort
Feb 15- Travel early to Tokyo to spend 2-days in Tokyo Disneyland
Feb 17 - early travel back to Osaka for a day tour then to KIX for return flight at 10:30PM

What do you think of our itinerary? Would you suggest a JR pass for that ? Does JR Train charge full for a 5y.o. passenger?

Thanks for your help.