Tokyo / hakuba / tokyo

Hi
I will be traveling to Japan this December.
I'm a bit confused as to purchase a JR East pass or just a normal tickets. Here is my itinerary for 2A&1C.
1) 3D2N - Hakuba (Narita - Tokyo - Nagano - Tokyo)
2) 5D4N - in Tokyo

Any suggestions?
What's the normal fare for Hokuriku Shinkansen? Any discount fare for child age 9?
To travel within Tokyo for 5D can I purchase N'ex round trip or just Suica card?

Hope to hear your kind advice.

Thanks.