Short answers, pulled from the story.
The name impala is first recorded in English in 1875 and comes directly from Zulu. An earlier English name, palla or pallah, first attested in 1802, derived from the Tswana word phala, meaning red antelope. The Afrikaans name rooibok, meaning red buck, is also used in English.
According to palaeontologist Elisabeth Vrba, the impala has continued in its basic form for at least five million years. The oldest known fossil ancestors were slightly smaller than modern impalas but otherwise very similar. Fossil species include Aepyceros datoadeni from the Pliocene of Ethiopia.
As of 2008, fewer than 1,000 black-faced impalas were estimated to remain in the wild. The IUCN classifies the black-faced impala as a vulnerable species. It is restricted to southwestern Angola and Kaokoland in northwestern Namibia.
Impalas use two distinct types of leap as an anti-predator strategy. One carries them up to 3 m high and 10 m forward, clearing vegetation or other impalas. The other is a series of bounds involving stotting, where the animal kicks its hindlegs mid-air before landing. Performing these leaps in changing directions likely confuses pursuing predators.
The impala rut is an annual three-week-long breeding season that begins toward the end of the wet season, typically in May. Mating tends to take place between full moons. Testosterone levels in rutting territorial males run nearly twice as high as in bachelor males.
Oxpeckers and impalas have a symbiotic relationship in which the birds feed on ticks from parts of the impala's body the antelope cannot groom itself, including the ears, neck, eyelids, forehead, and underbelly. The impala is the smallest ungulate known to be associated with oxpeckers. Studies show oxpeckers prefer the ears of impalas, where tick infestation is highest.