This is all idiotic. I can't believe Jews would misinterpret their own scriptures like this! Isaac was 37 when his mother died, and he got married at age 40 to Rebecca, which was 3 years later. Genesis 22:23 does not say that Rebecca was only 3 years old! Read the beautiful story in Genesis chapter 24 which describes how Abraham's servant went to Mesopotamia to find Rebecca and see if she would leave her family to marry Isaac. The servant met her as she had gone to get water from a well. You don't send a 3 year-old by herself to do that. She then drew water for all of Abraham's servants' 10 camels; a 3 year-old can't do that. She was then asked by her parents if she would consent to go and be Isaac's wife. She is called a "woman" and a young maiden throughout the story. To maintain that she was only 3 years old at the time is just foolishness. It sounds as if someone is trying to justify pedophilia...

Your point number 3

> The incident on Mount Moria (Genesis 22) and the birth of Rebecca happened at the same time, when Isaac was 36 (or 37) years old, same time when Sarah died.

is incorrect. Genesis 22:20–23 states:

> 20 Now after these things it was told to Abraham, “Behold, Milcah also has borne children to your brother Nahor: 21 Uz his firstborn, Buz his brother, Kemuel the father of Aram, 22 Chesed, Hazo, Pildash, Jidlaph, and Bethuel.” 23 (Bethuel fathered Rebekah.) These eight Milcah bore to Nahor, Abraham’s brother. 

The "after these things" refers to after Abraham's test with regard to sacrificing Isaac. After this incident Abraham learned that his brother Nahor had children, one of whom was Bethuel. Bethuel had then fathered Rebekah. At least 20 and maybe closer to 40 years (i.e., two natural generations) had happened by then, meaning Rebekah was likely closer in age to Isaac, who was 40, which would make sense. Also, remember that they didn't live in an era of instant communication like we do. They lived in separate countries now and didn't see each other again for years, if ever, and apparently letter writing wasn't a big thing.