Is it ok to use a 5v 1A AC adapter for a device when the original adapter is supposed to be 5V 500mA - will it damage the device?

Yes - what matters is the voltage - it has to be the same. The device will only draws 1A as needed - the adaptor with higher amp,i.e, 2A is fine. As long as the adaptor has amps equal to or greater than

those of the device, it will be ok!