In the Iliad, I suppose. The problem is that the era of warfare the Iliad describes and the era of warfare in which we have good, detailed accounts are very different. The Iliad is a bit of a temporal hodgepodge: it was written in the early Archaic period (800-500 BCE), was set in the Mycenaean Period (1600-1100 BCE) but took its cues from the Dark Age/Geometric Period (1100-800 BCE). Note that all of those terms and period divisions are modern and would not be recognized precisely by the ancients.
Or to put this in other words, Homer lived during a period in which states and political formations were emerging into the form that they would take during the Classical period. This had an effect on warfare, particularly the emergence of more organized forms of warfare--for example in the poetry of the Spartan Tyrtaeus, who lived perhaps a century later, the method of fighting is much more like the classical phalanx than the heroic combat of Homer. Homer is intentionally and explicitly nostalgic--his work is littered with references to essentially, how those were the times when men were men. So essentially he is describing the form of warfare practiced before the beginnings of the well documented phalanx formation.
Or to restate, yes we do have evidence that rocks were used in Homeric warfare--in Homer! Welcome to the world of Homeric studies.
This is a fairly well known paper on the topic that handles it in a much more nuanced and interesting was than I am doing here.
Depends on what you mean. Boulder throwing is a common tactic used in virtually all pre modern instances of siege warfare, and pre gunpowder catapults and trebuchets generally unlocked throwing stones too.
For individual weapons, slings were extremely common in warfare until the medieval era. Xenophon wrote quite a bit about slings used in combat.
But generally speaking, stones are cheap, effective and readily available add weapons, and especially useful in the ancient era. I would be surprised if the Greeks didn't use it, given its ubiquity all around the world.