reserving train travel in April

April 2014 - will we have trouble reserving the following trains in April.
Will reservations be easier with a green pass?
Also is the green pass useable and worthwhile for the following trips?
Narita Express to Tokyo
Hikara bullet from Tokyo to Nagoya
Limited Express Wideview Hida to Takayama
Limited Express Thunderbird Kanazawa to Kyoto
Hikari or Kodama bulet from Kyoto to Shin -Osaka
Sakura bullet Oasaka to Hiroshima
Kodama bullet train Nagoya to Odawara
Kodama bullet Odawara to Tokyo

Thanks - your advice will help me to decide whether to buy a green pass or an ordinary one.

Generally I don't think you will have any problems except possibly on April 14 from Nagoya to Takayama due to the Takayama Festival. For all other trains, you should have no problems making reservations if you do so a day in advance. And a lot of them will not book out, at all, making it possible to make reservations on the day itself.

Furthermore, all of the trains, except the Narita Express, have also non-reserved seating.