A3. No.
The Alternative Color function would not affect the overall color. This function changes only the color that you specify.
Use this function to change only certain parts of the picture, such as a logo.
To change the color shade of the whole picture, use the Tone Curve Adjustment function.
The Alternative Color function is a function to replace a color by specifying RGB values or CMYK values.
As such, if the same color exists elsewhere on the picture, the color of that unintended part is also replaced.
Before you replace a color, make sure that the same color does not exist elsewhere.