The Vulgate is a translation of the Bible into Latin made by Jerome. An accessible English translation that follows this tradition is the Douay-Rheims American version.
That depends on each individual compiler. Some are written in assembly, some in C/C++, others are written in whatever high-level language the author likes best.
According to Irishlanguage.net (see Link) under the headings: History of the Irish Language Stages of the Irish language It was developed before the 4th century