Buying (unreserved) traintickets?

I have a question concerning traintickets, hope someone here will be able to shed some light.

We will be doing alot of traintravel during our trip to Japan. Some of it is done on the Japan Railpass, but for the first part of our trip we dont have that.

Is it possible to buy unreserved tickets a day or a week in advance if you only know on which day you will be traveling and with which type of train (local/ltd.express/shinkansen) but not which exact train you will be able to take?

For example, we will be traveling from Odawara to Nakatsugawa (Kiso Valley) via Nagoya on Oktober 16th, and we know we will be taking a shinkansen to travel between Odawara and Nagoya and a ltd. express between Nagoya and Nakatsugawa.

It would be of great help if we could book these unreserved tickets in advance, as it would save us alot of time looking for a place to do so during our travel.

Thank you.

Is it possible to buy unreserved tickets a day or a week in advance if you only know on which day you will be traveling and with which type of train (local/ltd.express/shinkansen) but not which exact train you will be able to take?

Yes, it is possible. Just go to any JR ticket counter and indicate the route and travel date and that you do not need seat reservations.

If there is no long line-up, it is a matter of 2-5 minutes.

In regards to local trains, if you purchase local tickets from the vending machine, do it the day you travel, if I recall local tickets expire after x number of hours the same day. Since the vast majority of ticket machines sell local tickets, and the ticket machines are almost always near the entrance gates, it should not be a problem purchasing local tickets the day of travel.

Thank you for the replies John and Uji, much appreciated.

I have another question though.

Are the ticket vending machines on smaller stations like Nagiso/Nakatsugawa also in English? What about people at the reservation office in those places?

Most vending machines offer some sort of english translation.

For the train station staff it would depend. If you knew where you wanted to go and wrote it down then they could probably assist you better.

Regular local train tickets, just like any other regular base fare tickets are valid on one day (if distance covered is less than 100 km) or during a time period of two or more days (if distance covered is 100 km or more).

If you buy the ticket at a regular vending machine, the ticket will be valid for/from the current date. But if you go to a ticket counter (or use a vending machine with advanced options), you can specify a future date of validity.

It's really so easy and fast to buy train tickets right before you need them at ticket machines and counters. I wouldn't bother buying them in advance, especially for unreserved seats.