Train Tickets

Is everyone eligible to buy train tickets?
Where can I exchange my train ticket QR code for the physical ticket?
Can I board the train with the QR code? Should I exchange my QR code?
Can I modify my train ticket order after purchase?
What are the cancellation terms for train tickets?
What's the difference between Gran Class, Green Class and Ordinary Class?
What if my train is cancelled or delayed?
Why is the train route I want not available on your website?
What are the conditions for child train tickets? Can young children ride for free?
Why are there multiple train types for the same route ? (Hikari, Sakura, Nozomi, Kodama...)
Is there wifi on board the train?
Can I smoke on the trains?
Can I eat on the trains?
Is there a bar or dining car on the train?
Is a porter service available in the train station?