Yeah, you're right.
CullMode = None disables the backface culling, so polygons are visible from both sides.
AlphaTestEnable tells the shader to check the alpha of the pixel-shader's output. If it's higher than AlphaRef it sets the pixel's alpha to 100% if it's lower the pixel will not be drawn.
ZWriteEnable (in combination with alpha-testing) will prevent layering artifacts (this one is on by default afaik)

Using AlphaTestEnable should already include this, but you could add AlphaBlendEnable = False just to be sure that it's disabled.