Perception: The place of Sun rise and Sun set

Till, when he [the traveller Zul-qarnain] reached the setting-place of the sun, he found it going down into a muddy spring, ...
-- Sura Sura 18:86

Till, when he reached the rising-place of the sun,
he found it rising on a people for whom We had appointed no shelter from it.
-- Sura Sura 18:90

First: It is scientifically proven that the sun does not go down in a muddy spring.

Second: This seems to presuppose a flat earth, otherwise how can there be an extreme point in the West or in the East? It does not say, he went as far as possible on land in these directions and then observed the sun-rise or sun-set while standing at this shore. A sunrise there would be basically just the same as at any other place on this earth, at land or sea. It would still look as if it is setting "far away". It does say, that he reached THE PLACE where the sun sets and in his second journey the place where it rises.

Furthermore: Yusuf Ali in his commentary reports that Zul-qarnain is thought to be Alexander the Great. And so does the "Concise Dictionary of Islam." Looking at verses 98-101, this would make Alexander the Great a Muslim -- 1000 years before Muhammad. Yet that is for sure not true. The history does not relate that Alexander the Great had any other religion than the pagan Greeks he came from and ruled over. This is historically blatantly false.