Thank you for sharing your thoughts.
I am sure you have your facts all distorted.
Muhammad was not the founder of Islam,but the last Prophet and messenger among many which began with Adam(alaihi salaam).
Muhammed (peace be upon him)did not die of syphilis.Even his worst enemies during his time even if they did not follow Islam agreed to his intergrity,honesty,loyalness,purity and even used to seek his counsel in all matters of life until Muhammed(pbuh) called to submit to the One and Only Almighty God.
http://exposingdtruth.wordpress.com/...ihi-wa-sallam/
You may call whatever names you wish to call,but I am not going to call any names to Jesus (alaihi salaam),because I believe in him, not in the same way as you.And I await his descent to earth at the end of times to establish truth on this earth.
About the borrowing theory of the Quran from the Bible, you might like to read this link(or not).
Is The Bible Really The Source Of The Qur'an?
Many things will be similar to the original book revealed to Jesus(alaihi salaam) because the source is the same Almighty God.
As you said one of the fundamental differences between Islam and Christianity is that I do not go to Heaven by default for just believing as a muslim.
I have to work for it and it is upto the Almighty to admit me to Heaven or not.
I do not believe in someone else taking up the burden of my wrongdoings and being punished for it.I believe in equal justice on the day of Judgement.
Good and bad all will be justly paid their due on that day.