JR Pass

I have a few questions re JR Pass:
1) pls advise the link that I can make reservations online in English
2) If I made reservations already for a certain date & time, but I get to the station late and missed that train, I guess I could go to the ticket booth and reserve a seat on the next available train, is that correct?
3) If I prefer more 'flexibility' and did not make any reservations, does it mean that I can go straight to any JR stn and 'hop on' a non-reserved train car at any date & any time, and what I need to do is just showing my JR Pass at the boarding platform?

and even if all seats are taken, I am allowed to be on board that train, am I right?

pls advise the link that I can make reservations online in English

There is currently no website for making online reservations from outside Japan.

If I made reservations already for a certain date & time, but I get to the station late and missed that train, I guess I could go to the ticket booth and reserve a seat on the next available train, is that correct?

Yes. But you should try not to do that. The more pass holders who do not honor their free seat reservations, the more likely the Japan Rail Pass will drop the "free reservation" option in the future.

If I prefer more 'flexibility' and did not make any reservations, does it mean that I can go straight to any JR stn and 'hop on' a non-reserved train car at any date & any time, and what I need to do is just showing my JR Pass at the boarding platform?

Yes, that is right, except that you show your pass at the ticket gates (and possibly to the conductor inside of the train) rather than on the platform.

A small number of trains do not carry non-reserved seats.

Thanks Uji,

Of course we should not fail to show up, however my trip involves some highway bus connection with JR rail,and for some buses they don't have very frequent services a day. Even though I have a full Time Schedule right now, I guess I cannot do anything until I arrive in Japan to make sure seats is available in Higway Bus before I can go ahead with JR rail bookings.

I think that once you get to the station from the Highway Bus, you can go and reserve a seat on the next train. That way you don't have to worry about missing it.