JR East Pass (Nagano Nigiita area)

Day1: Narita Airport - Kawaguchiko *
Day2: Kawaguchiko - Tokyo
Day3: Tokyo-Nikko- Tokyo*
Day4: Tokyo- Nagano-Matsumoto-Tokyo*
Day5: Tokyo- Ibaraki(Hitachi Seaside Park) -Tokyo*
Day6:Tokyo-Karuizawa-Tokyo*
Can I use JR East Pass \17000 for this itinerary (5days *) + fare on Fujikyu Railway durng Otsuki -Kawaguchiko and purchase seperate ticket on day2 ?
Which one is better between JR East Pass and 2XTokyo Wide Pass? Please kindly recommend.

You can only use the Nagano Nigiita area pass up to Otsuki - it does not cover the Fujikyu train.
If you wanted to pay your way back to Tokyo (by bus or train) , you certainly could. As for getting 2 Tokyo Wide Passes, you could, but then you could not go all the way to Nagano or Matsumoto on them.

The Nagano Nigiita pass will pay for itself with just the round trip to Nagano and Matsumoto. And you save at least another 10000 yen on top of that with your other trips. Even if it doesn't cover Mt Fuji, it's going to be a good deal for you.

If it were me, I would use your pass to ride the NEX to Tokyo station, and then catch a direct bus to Kawaguchiko from there. Then you don't have to transfer as many times with luggage and it's only going to cost about 700 yen more. The same bus is probably the best way to get back to Tokyo the next day, too (1800 yen)

Thanks so much for both comments.