JR Tokai's Japanese website does have some information about the reservation up to 1 year in advance. Yes, not many details are available on the JR Tokai website so far. But the following is information from the JR Toaki website regarding one one-year advance reservation of the Shinkansen.

• One-year advance reservation of Shinkansen will be available only via the online EXpress Shinkansen reservation service.
• Only limited fare will be available from one year in advance. Possibly if you wait till the current one-month advance reservation, then there will be cheaper restricted discount fares available via the EXpress Shinkansen reservation system or other JR Tokai online services.
• Only a limited number of seats will be available for one-year advanced reservations. It is likely that a one-year advanced reservation is sold out but if you wait till a one-month advance reservation, more seats will become available.

It is highly likely that there will be a schedule change for a one-year advance purchase. If the ticket is for Tokyo - Shin Osaka, then there is Nozomi every 6 min. so schedule change may not be a big deal. If a reservation is for Odawara - Kyoto then schedule change can be a major change. The reservation will be made based on the current schedule and one month before the travel date specific train information and seat assignment will be sent online. Payment is due at the time of reservation is made, but does not say anything about the refund situation,

This is what is available online on JR Tokai and EXpress Shinkansen reservation websites.