yes
underpainting
Because they are harder and last longer.
Paint
Tempera is a low-grade paint and is very thin; oil painting is thicker, which makes it better for a variety of styles. Oil paint also had a slight reflective quality that is prized, whilst tempera is very matte.
Marble mostly. Then oil paint and tempera.
Tempera paint on a wood panel.
Until the early 15th century most artists did. Also later there have been many artists who prefer the qualities of tempera to oil paint.
To create layers of paint that reflected light
Yes, it is possible to put acrylic paint over oil paint, but it is not recommended to put oil paint over acrylic paint.
No, it is not recommended to paint acrylic over oil-based paint as the two types of paint do not adhere well to each other. It is best to use acrylic paint over acrylic paint or oil-based paint over oil-based paint for better results.
Egg tempera is a terrific medium with many advantages. It is safe, non-toxic, and permanent. Unlike oil paint, it will not yellow, change in color, or grow transparent over time. Unlike acrylic, it has a proven track record going back hundreds of years. Egg tempera shows the beauty of pigments off to great advantage. Colors are clear, bright, and pure. This is a terrific site that explains what-why-and how to make your own: * http://www.alessandrakelley.com/eggmedium.html
No, it is not recommended to paint acrylic over oil because the acrylic paint may not adhere properly to the oil paint surface.