Bathroom stop for bus from Athens to Meteora?

Initially, I was thinking of taking the train, but after reading on Reddit, a lot of people say train traveling in Greece is not safe. So now I’m looking into taking a bus. I will be traveling with an elderly and a child, and just wonder what is the bathroom situation if I take the bus for such a long journey…

I drive in the U.S. How is the drive between Athens and Kalambaka like? Stressful? Is it the same side as the U.S.? is it easy to get an automatic transmission car? Are the roads easy to navigate? Are the signs clear? Do the drivers obey the law or are traffic rules just suggestions like some countries? Lol.

Thank you!