Short answers, pulled from the story.
The earliest surviving illuminated manuscripts date from between 400 and 600 CE. These fragile documents emerged during late antiquity as the world transitioned from scrolls to codices.
Up to the 12th century most illuminated manuscripts were produced in monasteries within enclosed scriptoria. By the 14th century commercial urban scriptoria had almost fully replaced monastic production especially in Paris Rome and the Netherlands.
Blue especially ultramarine made from lapis lazuli was valuable and commonly used for depictions of the Virgin Mary. White lead created basic carbonate compounds historically made by corroding sheets of lead with vinegar.
Gold leaf applied to illuminated manuscripts became a defining feature starting from the 12th century when it was usually polished through burnishing. One popular method involved mixing gold with stag's glue then pouring it into water to dissolve with fingers.
Wealthy patrons commissioned luxury books like Books of Hours that separated one's day into eight hours of devotion. Philip the Bold probably had the largest personal library of his time in the mid-15th century estimated at about 600 illuminated manuscripts.