a) If Islam is God's perfected religion and God sent Jesus as a mere messenger, why is Christianity the world's dominant religion and has been nearly since its inception? Why would Allah do that?
From the concept of religion as detailed in the Quran, Islam is in existence since time immemorial. Since the question is about Islam, Jesus also was a prophet of Islam. Quran deems Islam as the Millat Ibrahim.
b) How is the Qur'an perfect and universal if it can only be studied and properly understood in Arabic? Also, why does the oldest copy not match up to any known copy we have today?
About Arabic, thats not a question. From what I know, Koine Greek, Hebrew or Arabic is not properly represented in translations. The Quran tells you to go to an expert if you dont know something. Thus, you can always refer to a learned person. We learn Koine Greek in the university in Bible studies. We learn Arabic and ancient Arabic in university. This is how it is.
What does little Christ mean? In India some are called Chinna Thurai. Small Boss. Thats the beauty of each language. This is the year 2016, the most widely spoken language chinese, then spanish, then English. One day this could change. You never know. If we survive for another 30,000 years, what language will we speak then?
Also, which oldest copy of the Quran does not match u to the copies today? Why do you say this?
c) Why do all the earliest Mosques face Petra? And why does Petra fit the descriptions given in the Qur'an, not Mecca?
All the earliest mosques face Petra? Another question will be is it Jerusalem!
Also when you say earliest is it during the time of Abraham? Or earlier. When you ask a question you should have a little more knowledge about the teachings of the religion.
Nevertheless your point is not taken. This idea is only an idea, doesnt have evidence.
Also, are you confident about the picture you have provided above? Let me ask you again, are you 100% confident about the picture you provided?
d) Provide me some non-Islamic evidence that Mecca existed in the time of Muhammad.
"Surprising as it may seem, not one map before 900 AD even mentions Mecca. This is 300 years after Muhammad’s death" http://www.academia.edu/1776803/The_Mecca_Question
There is no crystal clear historical evidence to the city of Mecca. There are only evidences taken from documents written years later. The Quran also does not refer to a city called Mecca. But there is no evidence to suggest the area was called by another name during that time either.
e) Why couldn't Allah preserve the original message and where were the supposed 24,000 messengers that were sent to everywhere? Evidence?
What do you mean the original message? You mean the Taurat, Zaboor, Injeel etc? Could there have been more revelations? Yes there could have been. Why didnt he preserve them? Well, how sure are you that they were ever written? Or are you suggesting the core message is not preserved?
Sending messengers to all nations is cited in the Quran. When you ask for evidence for this no one can provide. Its a theological matter. Not a historical matter. Also, there are many similarities still existing form ancient religions in various regions sometimes isolated and united through expeditions very late times after Muhammed. Thus there could have been earlier messages whos core messages have still survived. And can you provide evidence to state that there could never have been messengers of God sent to any nation outside the middle east or the old arabia?
f) Why isn't the word 'Muslim' or 'Muhammad' used during the Arabian conquests? Why do these words only appear years after Muhammad?
Maybe they didnt intend on lodging their names. Maybe whatever existed are lost or not found yet.
But there are two sheets of Hijazi script Quranic fragments from the 18th and 21st chapter in the University of Birmingham. You should go and see it. It has both names, Islam and Muhammed. Then it was found that france has another section of the same manuscript identified by various methodologies. Yes, the other earliest external document (Not a Quran) to mentioning the prophet Muhammed is from the year 671, around 40 years after he died. Now the first document to appear after Jesus from the bible is the p52 is date 125 - 175 (175 latest) while the Quran fragments are dated latest 645, that's 13 years after Muhammed died. But there is a significant possibility that this existed during Muhammeds lifetime. No other document that ancient, pertaining to a large religious group such as Christianity, Islam, Buddhism has ever been found. None.
Thats a long topic. But in short, Islam as a theology from a scripture called the Quran is more authentic than any major religion you can think of.
Cheers.