A staff member will go up and down the train with a service cart selling all sorts of things – soda, bento boxes, snacks and more. If you miss it simply wait until it passes again. Sometimes you'll find a menu in the seat pocket.
If you need to call someone, go to the area between cars. Don't talk on the phone when seated.
The flip-down table in front of you often has a map on it explaining where vending machines, restrooms and other things are located relative to your car.
If you're hungry, get a bento box at the station prior to boarding. They come in a million varieties. At major stations, they're often sold in various stores after the ticket gates.
English PA announcements are made prior to and after each station call on the Shinkansen. And most signs and displays on board are in English, too.
To get a ticket, find a ticket office and line up. Show your rail pass and tell them where you want to go and when. Most staff know basic English and it usually works out really well. The more you know, the easier it gets. Ticket machines only work when you're not using a Rail Pass.