You did not get an answer, so I will attempt an explaination. The shearwater 17 had simular instructions.   

Basically when they say : "(degree), beginning (inches) up the inside face, leaving half of the plywoods original thickness at the edge." 

They mean, draw a line on the inside face X inches from the edge, parallel to the edge. Now with a sharp plane, sandpaper, or your tool of choice, taper from the line to the edge, but only so that the edge becomes half the original thickness. I realize a picture would help, but I dont have the time nor tools to draw it. Hope this helps.

To make this concept easier to grasp, for example, the side and bottom panels meet at almost a 90 degree angle in the middle, so about a 45-50 degree bevel is required. At the ends, the same panels are almost flat, butted together, the bevel is there only to allow epoxy into the joint, so very little bevel is required. You should not cut your bevels into the outside veneer of the plywood. Some kayak kit manufacturers don't bevel the insde at all, leaving a gap for you to fill and round the outside edges later. Good luck, JRC.  

Understood now.  Thank you.  Its funny how somethinf simple can be misunderstood with a slightest question.  Now I read it and say to myself that makes perfect sense.  Thank you to all.