1. In the extra Jewish sources, show me something that testifies to the incident with Saul. Remember this is supposedly a well known story among the children of Israel! Show me the source!
2. No it makes no sense to imagine this. Unless you are saying Muhammad imagined the story?
3. The Quran claims over and over again to affirm the Bible my friend. Does it not even say at some point that it is an Arabic version of what is in the Torah? So the Quran should be verifying what the Bible says, so the tuquoque on the verifiability of the Bible story makes no sense.
Again the Quran is claiming to give a story well known among Israel. The exodus and Canaan are well known in Israel. Saul and the "water test" are not!
4. That is your problem not mine...the Quran is not even consistent on the question of how many days it took Allah to create the world. Six or eight?
5. My premise is correct because Allah tells your prophet to verify his stories using the Bible. So this is the premise of Allah, not mine and Allah himself confirms the stories in my Bible so I have no need for external confirmation. (Surah 3:3, 2:41, 2:101, 2:97, 2:89, 7:157, 5:46-48, 5:68,10:94 to mention a few)