This is called surface tension. When soap is added, it reduces the surface tension of the water, allowing bubbles to form. Bubbles pop when water evaporates out of the bubbles. Adding glycerin or corn syrup helps strengthen the bubbles by preventing the water from evaporating. If you want to touch a bubble without bursting it, wet your hand.
Bubbles are round when floating in the air because of air pressure.
The air outside the bubble presses inward while the air trapped inside the bubble presses outward. The colors you see when you look at a bubble are from light reflecting off the soapy coating on the water molecules. This soapy film is on the water molecules in layers, like paint in various thicknesses. Place tracing paper over a drawing that has heavy enough lines so tracing can be done easily. Dip the thin brush in the starch solution and trace the drawing.