If you're taking the Limited Express or Shinkansen, you need Suica and a separate ticket. You don't need a pass, in any case.

So the ticket that you said; do I buy it at the station?

Firstly, decide which train you want to take. I like a speedy way to get to my destinations so I take the Shinkansen or the Ltd. Express whenever possible. Some people want to save money and don't mind a slower train.

That said, to Hitachinaka, the express Tokiwa is available and you need to get an express ticket.

To Ashikaga, I would take the Shinkansen to Oyama. you need a Shinkansen ticket. You can buy these tickets at any JR station.