For the Samsung tablet you want a 2 amp (2000mA) or higher USB power socket.
Easiest way is a hella to normal adaptor lead and a car USB power thingy. I like the Griffin stuff, robust and a good fit into a lighter socket.
This setup would need to be in a tankbag as it isn't waterproof.
Beware of many of the motorbike specific power leads, often they are only 1A and the usb socket isn't go to thank you if out in the rain.