Yes, Old Testament, New Testament, Torat, Zaboor, The Bible were the genuine revelations before they were partially tempered with. The Muslims believe iin them being the Word of Almighty God. Actually the Religion given to mankind by Almighty God through holy Prophets (May peace be upon them all) is Islam, though it is named after the Prophets. The basis being the ONENESS of Almighty God. The manner of worship may be different but the basic beliefs are the same:
1. ONENESS of Almighty God.
2. Belief in the Angels.
3. Belief in the Prophets
4. Belief in the Day of Judgement
5. Belief in the life Hereafter etc.
No they are quite different.
Abraham was the father of the Jewish nation, as well as Islam, he was always obedient to god.
The old testament is common for Jews and Christians and not Muslims. However, Torah that is part of the old testament is common to Muslims.
It's the same God (Allah) as in the Old testament.
Judaism, Islam and Christianity all worship the same, SINGULAR God. The writings of the Jewish Torah and the Christian Old Testament are revered in Islam.
Judaism has that Tanakh [comprised of the Torah (Law), Prophets, and Writings] Islam has the Qur'an. The Hebrew Bible, or Tanakh in Judaism, is holy to both Jews and Muslims as well as Christians. In addition the Qur'an is the chief holy book of Islam, similar to the New Testament's role in Christianity. However, Muslims believe that the Tanakh as the Jews have it is incomplete (no New Testament) and is corrupted (no Ishmael sacrifice). Please read more at the Related Questions.
Hell is not mentioned in the Old Testament; the concept first arises in the New Testament and contemporary Rabbinical writings. The Old Testament generally refers to "Sheol" which appears to be much more similar to the Greek Underworld than the current concept of Hell.
The Christian bible has two parts: The old testament and the new testament. Christians believe that when Jesus came and died for our sins, he said that the old testament did not matter any longer. Judaism does not believe in Jesus, so they do not have the new testament. They follow the original old testament, which as I stated, is also in the Christian bible.
The Old Testament.
Apart from Christianity, you could say that all other religions do not accept the New Testament. (The religion that accepts the Old Testament, or Hebrew Bible, but not the New Testament, is Judaism.) It is also worth noting that Islam rejects the New Testament as written, but does not reject the spiritual nature of the events it describes. Islam holds the New Testament to be a corrupted form of Jesus's Ministry, something that is very important in Islam.
Yahweh, or Jahve (there are several similar spellings) is the name of God according to the Old Testament.
Ahmad is not mentioned in the Old Testament or the New Testament. Ahmad is an Arabic name and became popular after the Rise of Islam. If perhaps the person was looking for Ahab, he appears in 1 Kings chapters 16-22 and 2 Chronicles chapter 18.
Judaism: Tanakh (Hebrew Bible) Christianity: Bible Islam: Holy Quran