How do I get from Kyoto to Osaka using the JR trains? Can I just buy tickets at the JR Kyoto station?

yes it's easy. just buy on-day tix there. trains r very frequent. fr the Kyoto Station out to the Osaka station wil be just 30 mins train. i do took that train back & forth Osaka / Kyoto for a 1 day trip b4. v easy & convenience.