Should be no problem. Nowadays many small appliances come with a USB connecter. I have a desk lamp that I use which has a USB connecter to provide charging.
Jake,Just don't expect too much power out of it. Check what the ports are rated for (should be on the packaging, or in the tech specs).
Not a good assumption. It all depends on the power transistor they used to go from the mains to the 5vdc of the USB port. if they used a low wattage regulator, there won't be much power at the port. If they used a heftier regulator that costs more, it could be heartier. The fact it's connected to mains makes zero difference in this case.I would expect the opposite, they should be able to provide ample power for all devices over USB since they are connected to mains power.