Last night I reread an essay I read years ago about the use of language in First Century Israel by Joseph Fitzmyer. It is entitled "The Languages of Palestine in the First Century A.D." It was originally published in the Catholic Biblical Quarterly 32 (1970): 501-31.
In it he notes that the use of Latin was rare, although a Latin inscription naming Pontius Pilate as prefect found at Caesarea Maritima in 1961 is among the most famous archeological finds in that period. This is the one ancient find we have that names him.
Most importantly, Fitzmyer notes how widespread Greek was. Our oldest inscription is from 277 BC, observes that Esdras, 2 Maccabees, and additions to Esther and Daniel were composed in Greek. Josephus and Justus of Tiberius wrote in Greek, but Josephus needed some help of assistants to do it. Epigraphic materials come in a variety of forms: the prohibition of Gentiels to enter the Holy Place and the Theodotus inscription of a synagogue dedication being the most famous of these. Many ossuaries (burial boxes) show up with Greek inscriptions. Materials from Murabba'at and Wadi Habra also show use of Greek. He thinks it likely Jesus spoke Greek, fitting its "widespread" use in the region, including towns with use by farmers and tradesmen.
Aramaic was the most widely used language, and there was some evidence of usage of Hebrew. The presence of targums (Aramaic translations of Scripture) shows that Hebrew was not as widespread.
This means that there is a likelihood as well that the merchant disciples (fishermen, tex collectors, etc) would likely have had some knowledge of Greek. The picture of these followers of Jesus as illiterate (as Bart Ehrman argues, for example) is not so likely.