Shinkansen Bullet Train to Karuizawa

Would i still be able to get a ticket for the bullet train to karuizawa via the Hokuriku Shinkansen line on the day of departure because i am only touching down late the night before?

Would you recommend me to reserve a seat?

Lastly, would it be better if i were to purchase the JR Kanto Pass or just purchase the normal 2-way train tickets from the ticket counter/vending machine?

I am very confused by which train to take because kagayaki, hakutaka and asama all goes to karuizawa.

Thanks in advance for you help! Really appreciate it :)

Would i still be able to get a ticket for the bullet train to karuizawa via the Hokuriku Shinkansen line on the day of departure because i am only touching down late the night before?

Yes! All trains to Karuizawa have non-reserved seats.

Would you recommend me to reserve a seat?

It's personal preference. I always travel with a seat reservation for peace of mind. But between Tokyo and Karuizawa it is not mandatory.

Lastly, would it be better if i were to purchase the JR Kanto Pass or just purchase the normal 2-way train tickets from the ticket counter/vending machine?

Regular tickets for a round trip between Tokyo and Karizawa are more expensive than a JR Kanto Area Pass. Note that he pass will become the Tokyo Wide Pass from December 19. It will become more expensive, but is still cheaper than regular tickets. So, i recommend to get the pass.

I am very confused by which train to take because kagayaki, hakutaka and asama all goes to karuizawa.

No, the Kagayaki does not stop at Karuizawa. Only Asama and some Hakutaka trains stop there. Use the following website to look up connections:
http://www.hyperdia.com/

Basics about the Hokuriku Shinkansen:
http://www.japan-guide.com/e/e2018_nagano.html