vtol aerodynamic unit and cp, area

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<plugin name="lifting_surface" filename="libLiftDragPlugin.so">

    <!-- taken from the lift curve figure -->
    <!-- alpha_0 is 5 degrees -->
    <a0>0.08727</a0>
    <!-- alpha_stall is 19.3 degrees -->
    <alpha_stall>0.3368</alpha_stall>
    <!-- slope of the lift curve to the left of the stall angle -->
    <cla>5.418</cla>
    <!-- slope of the lift curve to the right of the stall angle -->
    <cla_stall>-2.1419</cla_stall>

    <!-- below are just random values in this example -->
    <cda>0.0</cda>
    <cda_stall>0.0</cda_stall>
    <cma>0.0</cma>
    <cma_stall>0.0</cma_stall>
    <area>3</area>
    <fluid_density>1.2041</fluid_density>
    <forward>-1 0 0</forward>
    <upward>0 -1 0</upward>
    <cp>0 0 1</cp>
    <link_name>lifting_surface_link</link_name>
    <radial_symmetry>false</radial_symmetry>
  </plugin>

1. What is the unit of area here?
2. I'm curious as to which area exactly represents the area. If you have a formula please let me know
3. Is it correct that the parameter value of cp represents x y z and What is the unit of cp here?