Hebrew
The scroll inside the mezuzah is written in Hebrew.
Me'gee'la מגילה
scroll book = מגילה (megillá)
It could be Hebrew or Aramic.
Yes they are.
"SAY-fair TOH-rah" ... meaning "Torah book"
scroll = megilá (מגילה) The phrase "Torah scroll" is often translated as séfer Torah (ספר תורה)
It wasn't the Jews (plural) who wrote the first Torah, it was Moses, at God's dictation (Exodus 24:12, Deuteronomy 31:24). See also the Related Link.How did the first Torah-scroll come to be
For those who are not fluent in Hebrew, it is hard to read the Torah as the Torah scroll does not have nikkudot (pronunciation indicators).
The special Hebrew stick is called a "mezuzah." It is a decorative case that holds a scroll inscribed with specific Hebrew verses from the Torah, particularly the Shema prayer. Mezuzahs are affixed to the doorposts of Jewish homes as a sign of faith and a reminder of God's presence.
That word does not mean anything in Arabic. Chumash in Hebrew refers to a book-copy of the Torah scroll.