Jungfrauch

I would like to go to Jungfrauch in the first week of June.
1)Do I need to make reservations on the Jungfrauch railway? I dont yet have a Swiss pass but plan to buy one soon or on arrival at Zurich.
2)Can I make the reservation without the pass?
3)Which is the cheapest way to get to Jungfrauch frm Interlaken OST?

Hello swisstraveller,

1 & 2) You don't need reservations, please see here for details.
3) Your Swiss Pass gets you to Wengen for free. All you need is a return ticket from Wengen to the Jungfraujoch, and you'll get a discount on that ticket.