train from Narita Airport to Ski resort

I'm planning day trip in late Dec to Gala Yuzawa for ski from Narita Airport. These are the trains and transfer that I need to take to reach the destination
1) Keisei Sky Liner from Narita to Nippori, then
2) Either JR Yamanote Line or JR Keihin-Tohoku Negishi Line from Nippori to Ueno, then
3) SHINKANSEN from Ueno to ECHIGOYUZAWA (or Gala Yuzawa).

How far are the platforms from each other for each of the transfers I'm taking ?
Can I purchase all these train tickets together at Narita airport station ?
The 3 trains that I'm taking is from different rail line, do i have to buy separately or can buy together ?
Do I buy SHINKANSEN ticket at the same vending machine as the others ?

1) Keisei Sky Liner from Narita to Nippori, then
2) Either JR Yamanote Line or JR Keihin-Tohoku Negishi Line from Nippori to Ueno, then
I assume you get off at Nippori because you don't want to walk from Keisei Ueno to JR Ueno staion with a big luggage, right? (Keisei Skyliner directly takes you to Ueno station. But it takes about 10 min from this station to the platform of Shinkansen)
Keisei Nippori to JR Nippori is the same station. Take upward escalator, pass the transfer point and take downward escalator. 3-4 min is enough.

Can I purchase all these train tickets together at Narita airport station ?
You can buy tickets at the airport but buy them seperately.

The walk from the Yamanote Line platform to the shinkansen platform is also about 5 minutes or more.

I would rather take the Skyliner to Ueno and transfer to the shinkansen there. It is about a 10 minute walk from Keisei Ueno Station to the shinkansen platform, as mentioned by JLady, but it is one transfer fewer.

The most comfortable route would be by Narita Express via Tokyo Station.