Short answers, pulled from the story.
Primates are an order of mammals divided into the strepsirrhines, which include lemurs, galagos, and lorisids, and the haplorhines, which include tarsiers and simians. Simians cover monkeys and apes, and apes include humans.
There are between 376 and 524 species of living primates, depending on the classification used. New species keep being found, with over 25 described in the 2000s, 36 in the 2010s, and six in the 2020s.
Primates arose between 74 and 63 million years ago from small terrestrial mammals that adapted to life in tropical forests. Some molecular clock studies place the origin of the primate branch earlier, around 85 million years ago in the mid-Cretaceous.
The smallest primate is Madame Berthe's mouse lemur, which weighs 30 grams, and the largest is the eastern gorilla, which weighs over 200 kilograms.
About 60% of primate species are threatened with extinction, driven mainly by large-scale tropical forest clearing for agriculture. Other threats include forest fragmentation, monkey drives, and hunting for medicines, pets, and food.
Yes, several primates make and use tools. Jane Goodall observed chimpanzees fishing for termites with grass in 1960, and capuchins, crab-eating macaques, and orangutans have all been documented using tools in the wild.
Catarrhines are routinely trichromatic due to a gene duplication of the red-green opsin gene 30 to 40 million years ago. Among platyrrhines, trichromacy depends on a female being heterozygous for two opsin alleles on the X chromosome, so males can only be dichromatic.