Takayama-Hokuriku Area Pass enquiry

Hi,
how are the chances of getting on board the bus for 6 pax
if I only book the bus at Takayama station at 10 am for going to Shirakawago?

Also, can I book the bus ticket at Takayama station for the bus direction from Kanazawa to Shirakawago 2 days later trip?

I have never been to Shirakawago before hence I have no idea how famous will it be at late may's weekday
period.

This pass cost 5 Day = 19800 yen
Valid JR,bus in Nagoya,gero ,takayama, toyam a,fukui, kanazawa, osaka,kyoto,kansai airport
So your First duty is To buy the pass,then you will found A lot of japanese will help you,besi de JR Staff,applicable bus staff in valid area