Greece

Being Greek meant that you spoke Greek. There were several dialects used by the different peoples who made up the Greek world - mainly Aeolic, Doric and Ionian, but it became based on Classical Greek 2500 years ago.
The ancient Greeks spoke a language that we call Ancient Greek.
Ancient Greece people speak Greek and who ever didn't know that now knows.
Greek.
In Ancient Greece, people spoke Ancient Greek--for the Archaic and Classical periods. For the time period around Alexander the Great and the New Testament, a language known as Koine Greek was spoken.
Basicall, yes, however like English today, there were many dialects.
Greeks spoke ancient greek in ancient times, which has slowly evolved into modern greek
Only if their professional life required it. The word 'barbarian' applied to non-Greeks derived from a saying that foreign languages sounded like 'bar-bar-bar'.
Originally, ancient Greece had several different languages and dialects. The main three languages were Aeolic, Ionic and Doric, with their various dialects.

When Athens came into power, Attic Greek was spoken. Attic Greek is the language of the Greek classics.

When Alexander the Great amassed his army, he standardized the language so his troops could understand one another. This became Hellenistic Greek or Koine Greek. This was the Greek that became the cultured and diplomatic language of the ancient world. This is the language of the New Testament and the Septuagint.
greek

Unlike modern authors, Homer is not quick to reveal his personal beliefs; rather, they come about subtly, through the dialogue between two characters or through implications of epic similes. He wants the focus of The Iliad and The Odyssey not to be to extract his opinions but to develop one's own conclusions about life, religion, the natural world, and the interplay between the three.

That being said, Homer is human and does have beliefs.

On mankind: Homer was a strong proponent of a collective human race, as is apparent in his removed commentary on the Trojan War in The Iliad. Rather than take a side in the Greek vs. Trojan conflict, he portrays the strengths and the shortcomings of the characters on both sides with striking honesty. He feels that while humans have their limitations and inclination towards sin, they also have the propensity to display bravery, loyalty, and grace.

On religion: The idea that all Greeks believed in the Greek gods is a widely held misconception. In fact, the worship of the Greek gods were considered more of a superstition/custom (similar to modern-day practices of knocking on wood, avoiding ladders, etc.) than organized religion. We do not know what religious views Homer held; however, many scholars think that he did believe in some sort of life-force.

On values: In both of his epics, Homer emphasizes many traditional Greek values: xenia (hospitality), kleos (glory), and metis (wisdom),among others

Arges,

Steropes, and

Brontes

Persia never conquered the whole of Greece and the bits that medized (submitted to Persia) were quickly intimidated back away by the major powers of Athens and Sparta. Persia kept trying to conquer Greece because, simply, it was described to Darius and Xerxes as the most beautiful place in the world, and they wanted it.