Giotto used tempera type paints - pigments with a binder of egg yolk or sizing. He painted wet plaster (fresco) or on wood.
No it was painted with tempera.
I suppose if you were doing a faux fresco you could use tempera paint, but this wouldn't be done using plaster but on paper in the same style. On plaster I don't think the tempera would work.
secco
yes
Tempera paint on a wood panel.
Frescos are painted directly onto wet plaster.
It's painted with "tempera", water and egg based paint.
Frescos are painted directly onto damp plaster on walls.
Plaster itself is not poisonous. Some people are allergic to it but generally you will only have a reaction to it if you consume it. Plaster of Paris may cause breathing difficulties if inhaled. Wall plaster is harmless once it is painted and/or covered, and contact with it before that is fine. Painted wall plaster is safer as it does not release dust.
It is difficult to say if you cannot tell me where you have seen it. This subject was painted by lots of artists. If it is Italian it is probably painted with tempera paint on wood.
Frescos are murals painted onto plaster. Buon fresco, the technique of painting on wet plaster, creates vibrant colors and lasts a long time. Fresco secco, the technique of painting on dry plaster, does not last nearly as long.