THE RELIGION GUY’S ANSWER:
That first one is easy: Aramaic.
As writer Philip Koslowski stated January 21 on the international Catholic aleteia.org, it was the common language spoken by Jews in the 1st Century Holy Land. There’s virtually no doubt Jesus would have taught in that tongue.
For one thing, the original Greek New Testament carried over numerous Aramaic words, especially in Mark and Matthew. Our Gospels in English are translations from Greek that report sayings Jesus would have uttered in Aramaic -- something the experts continually ponder.
Question #2 is more complex. On literacy, there’s no way to know for sure whether Jesus could read or write Aramaic.
Scholars like England’s Chris Keith and America’s Bart Ehrman think it’s most probable he could not read and write. On the popular level, Reza Aslan asserted this in his heterodox Jesus biography “Zealot,” which was so lauded by the “mainstream” media. (Yes, he’s the Muslim-turned-Christian-turned-Muslim-again that CNN then hired to host a religion series but sacked over his profane tweet assailing President Donald Trump.)
As an aside, note that Random House promoted Aslan’s book as “balancing the Jesus of the Gospels against the historical sources” instead of “other historical sources.” Such sleight of hand excludes the Gospels -- our earliest and most extensive material -- from the historical materials regarding Jesus.
Whatever Jesus’ skill with written Aramaic, one Bible passage indicates he had some working knowledge of Hebrew, the language of the Jewish Scriptures and used by the religious elite.