No, gotta put your credit card info into the wallet app before use as it needs to verify it's your account. Also, Apple Pay doesn't accept all cards. My main card isn't accepted, which is sad.

Way before I ever tried, I had seen videos of RFID "contact less" demos where you tap the device to the machine. Like at a gas pump. The icon usually gives you a clue to tap as well, but I suppose you have to imagine it is even a theoretical possibility.

I don't think there is way to make it discoverable without a big sign saying tap here ↓. Not from the phone anyway. Just something children will see and in the future never think twice about.