4. Why is there no historical criticism of the Quran - (as there is of the Bible)?

There is a misunderstanding:
The Bible is made up of many different parts, compiled over many centuries and it is possible to cast doubt upon one part without impuning the rest,

whereas the Quran is a single revelation, received by just one man, either you accept it for what it claims to be, in which case you are a muslim or you reject this claim, and so place yourself outside the fold of Islam.