I've been researching this a bit more and the documentation is a bit confusing.
I'm thinking the best way to power would be through the USB port. Just take a USB cable and cut the end off.
Or is the 5V where I would connect. But I see it would be advisable to add a diode.
If the 2560 is powered from with a through the barrel connector does the 5V become a reference voltage?
Is the Vin for 7-12 v input/same as the barrel connector?
Thanks