can you buy tickets to the grand ole opry the day you get there, or do you have to buy them ahead of time?

Yes u can get tickets at the door

You can, some people did while I was staying this past weekend ... I'd pay in advance though unless your not entirely sure

I would purchase in advance. The show sells out and you won't get the seats you want.

Not that I remember. Assuming they are not sold out already, they want to avoid seating the day of because of the amount of people. No one actually dictates your seat with a computer. It's like a stadium, you find the seat that you bought. Not entirely sure though. "As an event start time approaches, please purchase your tickets directly from the Opry Box Office as online and phone sales will be cut off at varying times based on event time." From their website. So I would say better see if their seats first, then go to the office and ask.

Depending on the time of the year, the Opry can sell out quickly, however, you can get lucky and purchase tickets at the box office day of... most people don't like top risk it.