1.) No, nothing is wrong with those commands. Say you have a purely white sprite, the following examples will change its color:
+ Code Snippet // Solid Red
setSpriteColorRed(sprite, 255)
setSpriteColorGreen(sprite, 0)
setSpriteColorBlue(sprite, 0)
// Solid Green
setSpriteColorRed(sprite, 0)
setSpriteColorGreen(sprite, 255)
setSpriteColorBlue(sprite, 0)
// Solid Blue
setSpriteColorRed(sprite, 0)
setSpriteColorGreen(sprite, 0)
setSpriteColorBlue(sprite, 255)
You may find it easier and more efficient to use setSpriteColor(r, g, b, a).
+ Code Snippet // Yellow at 50% opacity
setSpriteColor(sprite, 255, 255, 0, 128)
2.) You can change the backdrop color via the SetClearColor(r, g, b) command. If you want a solid red background, you would use: SetClearColor(255, 0, 0)