Short answers, pulled from the story.
Mycenaean Greek is the oldest known Greek dialect. It is attested from Linear B tablets produced by the Mycenaean civilization of the Late Bronze Age in the late 2nd millennium BC. Mycenaean was deciphered only in 1952.
Ancient Greek dialects developed because of isolation and poor communication among communities living in broken terrain. The collapse of the Mycenaean civilization in the early Iron Age scattered Greek speakers across mainland Greece, the Aegean islands, and the coast of Asia Minor, letting regional speech patterns diverge over centuries.
Homer wrote the Iliad and the Odyssey in Homeric Greek, also called Epic Greek. It is a literary dialect that blends Ionic and Aeolic features and is composed in dactylic hexameter. Hesiod used a similar dialect, and later epic writers such as Apollonius Rhodius and Nonnus imitated this convention.
Arcadocypriot is the ancient Greek dialect spoken in inland Arcadia and on the island of Cyprus. It is the only ancient Greek dialect with a known Bronze Age precedent, descending from speakers of Mycenaean Greek who were either displaced to Cyprus or remained inland after the collapse of Mycenaean civilization.
Attic Greek, the dialect of Athens, was adopted in Macedon before the conquests of Alexander the Great. As Hellenism spread, Attic became the basis for Koine, the common Greek of the Hellenistic period. By the first few centuries AD the Attic koine had replaced the other regional koines in everyday speech.
Tsakonian is regarded by some scholars as the only modern Greek dialect that descends from Doric. Pontic Greek retains certain Ionic elements. The Southern Italian dialects known as Griko and Calabrian also preserve some Doric features, though they may descend from a Doric-influenced variant of the Koine rather than from Doric directly.