I've seen that website hundereds of times. The forum is vile and pointless, just full of hatred. There should be a degree of respect for people. I feel sympathy towards islam for reasons you would not know of, feelings not words on a piece of paper.
The debates are however very good but lack a final touch.
Hajar, the religion you were born into stands for, teaches, and commits thousands of vile and horrific deeds each and every day, a good portion against its fellow Muslims. Look at the Sunni/Shiite war within Iraq today. Do you see Protestants and Catholics firebombing each other's churches every single day anywhere in the world today?
The fact that your immediate family and friends may not have partaken in them does not mean that most have not or that they wouldn't support them being done (i.e. suicide attacks in Israel, Iran's nuclear program, etc.). You are a young lady and need to decide where you want to go in life and what you want to believe. The Lord does not judge you for the background you were born into; he judges you for what you choose to follow and hold true once you are old enough and have the facts to make up your mind. You have a decision to make. We are here to help you, and are your friend, but we will never, ever attempt to downplay Islam, what it or Mohammed taught/teaches, or what its followers do.
You yourself acknowledged that some Islamic teachings are based on Judeo-Christianity. That is absolutely right. Mohammed was shrewd enough to know that he needed to make some attempts to pay homage to the prevailing monotheisms of his neighbors in order to sound legitimate and gain their support and get them to follow his new cult, so we do have crude references to both Testaments here and there in the Koran. That's all it is--plagiarism. Islam is based entirely on the pagan polytheisms of the Canaanites, Midianites, etc. of the Fertile Crescent, who are of course the ancestors of today's Arabs. Allah is the moon G-d of the Fertile Crescent (Sin), and Mohammed merely deleted the lesser deities in that system (Sin's daughters). The reason why Islam today is so ferociously cruel and warlike is simply because that is how the Canaanite religion was as well. Remember, these were people who burned their children alive as a sacrifice to their gods and who had tried to exterminate the Israelites as they came out of Egypt.
Edit: You and Sarah are not actually half-Arab, but half-Berber. Like all nations and races they came upon, the Arabian Muslims utterly vanquished and subjugated the Berbers in their westward jihads and forced them to Arabize and adopt their language and culture.