I am extremely excited to play this! I have a question w/r/t fuel for Rigs; specifically, do they require fuel in the same way as the vehicles in the tables on pp51-52? Or is this explained somewhere in the book and I'm just bad at reading? I noticed there's a reference to a Rig using fuel on the Valyri Göth character sheet but couldn't find any specifics in the book. Thanks!
There's nothing wrong with your reading skills. In an older version of the layout, the war rigs were on the vehicle chart but I moved them to the armor section to emphasize that it's a suit that you wear and not a vehicle that you drive. Learning to move and fight normally in a rig is more a matter of athletic adjustment than learning a piloting skill.
I'll be fixing some errata and uploading a corrected version of the book soon. Standard rigs have a fuel tank that holds 12 slots of fuel, like the ruggedized motorcycle. The Warrior starting packages should also state that any vehicles or rigs start with half a tank. The vehicles & travel section on page 52 still includes the fuel expenditure of rigs: they're very efficient, but don't carry much with them. If you have a player that likes to count all the copper pieces, they can have some logistical fun in figuring out when it's better to make the war rigs walk or ride in the back of a truck.
The "cargo box" war rig mod is big enough to hold a 5-gallon jerry can and I would allow a player to use it as an extended fuel tank by doubling the cost to account for extra fuel lines and such. (Or they could just keep a jerry can in there and get out of the rig to refuel.)