The specs don't say specifically that it's a micro usb, and none of the pictures on their webpage don't show the port, but Engadget claims that it's micro-usb.
http://www.engadget.com/products/ama.../voyage/specs/
....and micro-usb is micro-usb, as long as the charger puts out sufficient amperage. A 1 amp charger is probably sufficient. A higher amperage will not harm the device, it just means that the charger COULD put out more than the device is pulling. Less would mean that it can't keep up with the demand of the device. As for voltage, that's constant across all USB chargers as the standard defines it.
That said, cheap generic chargers can be dangerous as they don't have sufficient isolation and can cause fires or shocks, not to mention non-constant output that can damage your devices, so avoid super cheap generic chargers.
edit: DON'T show the port