Nice one!

Three additions, if I may be so bold:

• The shape of the aperture blades and the number of blades also play a role, in bokeh and starbursts. Some lenses have almost straight blades, some have curved blades. This is why some lenses won't do proper starbursts whatever you try, but sometimes that can be a Good Thing, as starbursts are also artefacts.
• Using very small apertures, say beyond f11, can cause diffraction, making the image less sharp, so a smaller aperture isn't always better for sharpness.
• A smaller aperture can eliminate lens distortion and other problems; some lenses aren't very good wide open.