Ans.1. Allah is just Arabic for the word God. In an Arabic Bible, God is said as Allah. Muslims can say Allah and God all they want.
2. Speaking of Allah also being used in Muhammad's past pagan religion, do you know what else clearly came from his past pagan religion? Honor for the Kaaba and the Black Stone and belief in the Jinn.
3. The interesting thing about Muhammad was at first he agreed that people should face Jerusalem for prayer,
04. It's clear that the Quran had to be revealed over 23 years because Muhammad's circumstances kept changing and as it did, out comes a new Sura.
05. Sura 5 should have been the end of the Quran where "God" said he has now completed his favor and completed their religion ..
Any 5th grader can figure out how obvious this is, but Muslims NEED Islam to be true, so they are totally blinded to this.
01. In fact every revealed religion worship the same deity. But due to effect of age and time, the concept gets corrupted due to wrong interpretation of scholars and followers.
Since Quran is the last revelation and it is preserved in its original condition, the concept of God in Quran is purest and best that any Monotheistic religion can produce.
02. Kaaba was House of Allah constructed by Prophet Abraham and Ishmael. It were they who started the ritual of Hajj.
Our prophet did not come to destroy the good practices and good things of teachings of those prophets.
Everything that Makkah people did was not "pagan". Wherever they deviated, our prophet corrected it.
There is no statue left in Kaaba and building of Kaaba and black stone there are no statues.
03. When our prophet started his mission, Kaaba was filled with 360 idols, if he faced towards Kaaba, people would say that he was praying to idols.
That was the reason he was asked by God to face towards Jerusalem, the direction of prayers of Jewish and Christian prophets.
As an Arab he wanted to have the direction of prayer should be Kaaba the house of his patriarch prophet Abraham. But it was a test from allah for him as his followers, as to whom they obey. Their Allah or their own wishes.
After testing the faith of Muslims for 17 months in Madina, Allah asked Prophet and Muslims to change their direction towards Kaaba.
This was a declaration that Jews and Christians are removed from their "chosen status" and Quran says that "Jews and Christians Know that this decree is from their Lord"!!
Jesus warned them "This cup will be taken from your hand and given to others" !!
04. Quran took 23 years to be revealed, because it was to be the "Final guideline" for Humans till the end of time.
You are right, the circumstances of prophet's mission changed and the Quranic verses gave directions for each of them.
So not only prophet and hundreds of his companions memorized the whole Quran but knew how to act on each verse too.
This would not have been possible if "entire Quran" was sent down in one instant.
05. Surah 5 was indeed one of the last Surah to be revealed and the verse where Allah says 'I have completed the religion.." was revealed on the Arafat day of Farewell Pilgrimage of prophet, and Prophet only lived less than three months after that. May Allah have Mercy and Blessings on his noble soul.
Who told you that arrangement of Surah in Quran is as per their chronology of revelation?
Chapter 9 was revealed before Chapter 5