How can the Almighty's saying: "And the earth, after that, He spread it out (dahaha)" be reconciled with the scientific fact that the earth is egg-shaped, and why is there a contradiction in the different narrations of the hadith "A good vision is a part of prophecy"?

A scientific fact cannot contradict the established texts of revelation. The word "daha" (دحا) in the noble verse does not contradict the sphericity of the Earth, as the "dahu" (spreading/flattening) and "bast" (extending/spreading) here are as they appear to the observer. As for the various narrations in the Hadith stating that vision (ru'ya) is a part of prophecy, the intention behind them is to magnify the vision of the righteous believer, and that it is one of the parts of knowledge that came to them and the tidings with which revelation descended upon them. Some visions are clear and do not require interpretation, while others do. The highest among them are those for whom the number of parts separating them from the degree of prophethood is the smallest reported, and the lowest are those for whom it is the largest. Just as the prophethood of prophets varies, so too does the vision of the believer.