Your basic question is uncontroversial. The Old Testament is predominantly written in Hebrew, with a few portions (parts of Ezra and of Daniel) in Aramaic. The New Testament was written in Koine Greek. I don't see how you could get conflicting reports on that, it is beyond reasonable doubt.

Where, when, by whom, and why are much more complex questions, and in fact should generally be dealt with on a book by book basis. Each book in the Bible originates in its own context, with a particular purpose, by one or more authors and/or composers/editors, sometimes over a period of time.

The old testament was written in Hebrew, hence the name the Hebrew Bible. Jewish kids go to Hebrew school so that they can read the torah, the first five books of the old testament. The New Testament was written in Greek, but Latin is the official language of Catholicism because it grew up in the Roman Empire, (hence the name Roman Catholic Church) so a lot of church writings were in Latin. Interestingly enough, the Latin Vulgate was originally supposed to be a version of the Bible translated into the common (vulgar) tongue, and st. Jerome was canonized for translating the Bible so that the common people could read it, but then during the renaissance the Roman Catholic Church insisted that the Bible not be translated because its only pure form was the original Greek and Latin texts. The Vulgate has been criticized heavily for being filled with errors, so most non-Catholic Christians and a bunch of Catholics only defer to the Bible and disregard the Vulgate.