If it only takes 1 mm of movement to transfer from whole bike to half bike, does it require more sustained effort to keep yourself in just the right position (so that neither wheel A nor C touch the ground) than the effort used in a regular bike?
You also have a serious logic flaw in your answer to the first question, one which makes your design assumptions incorrect. Friction is based on the contact force between surfaces. For a normal bike, the weight of the rider (W) is split between the 2 wheels. This means you have W/2 on each area of tire, A, for a traditional bike. So the total friction is
F = (W/2 * A) * 2 = W * A
For a half bike, all of the weight is on one tire, so the friction is
F = W * A
So your assumption is wrong, in theory the friction force is the same! Now lets look at reality - the weight on a tire affects the amount of tire that touches the ground. The tire will have a tendency to "squish" down under more weight, making more tire contact the ground with more weight. So in a normal bike, only half of the weight squishes each tire. Your half bike puts all of the squish on one tire, so in actuallity your half bike causes MORE friction between the tire and the road.
Also, did you do this website? You should check your spelling and grammar.