I'm so glad to hear that! I feel very fortunate to have seen the Kamogawa Odori, and hope you find it as special as I did.

>>bus to S-go between Takayama and Kanazawa

Those buses might have reserved seats.

>>to understand all the bits and pieces.

A couple more pieces of the hyperdia puzzle, FWIW:

At HyperDia the route description shows a seat fee, for example this for Toyama->Kanazawa
Seat Fee:¥ 2,360

To the right of the train name is a drop-down showing options.
The default is: Reserved seat ¥ 2,360
Below that is: Unreserved seat: ¥ 1,840

The difference, ¥520, is the cost of a seat reservation.

The ¥1,840 is the limited express surcharge as mentioned above.

"Fare" is shown in two places. This is the base fare and what you would pay if you took ordinary trains. Fare:¥ 970 for Toyama-Kanazawa.

I think that last-minute reserved seats would be available and also not worth it. There should be a good number Tokyo pax getting off at Toyama and not as many boarding.