JR Kanto or (Suica + NEX) card

Hi there,

Our itinerary is 2 Feb 2014 arrive at Narita, then need to go to Karuizawa straight away. Stay karuizawa from 2- 5 Feb, then need to go back to Tokyo. Stay in Shinjuku from 5-8 Feb 2014 when we depart Narita.

1) What type of train pass should we get?

Will it be (Suica + NEX) card where we take from Narita to Tokyo and then buy individual shinkansen ticket from Tokyo to Karuizawa at $5750 (1 way) and then use the Suica card to travel around Tokyo city and then back to Narita airport on day of departure,

any other better options available?

2) JR Kanto pass is vlid for 3 days. What is 3 days? 2/3/4 Feb???

Thanks.