Minato could be developed further by exploring his time as the Fourth Hokage more deeply. For example, show his political decisions and how they were influenced by the presence of the Kyuubi. Also, his relationship with other villages could be explored, especially in relation to the Kyuubi's power. Maybe he had to make some tough calls to protect the village from those who might want to use the Kyuubi for evil.
Well, it depends on the specific fanfic. Some fanfics might really emphasize Naruto's growth to be on par with Minato in terms of smarts. They could show Naruto learning from Minato's memories or having some sort of spiritual connection that transfers knowledge. However, other fanfics might focus more on other aspects of Naruto's character and not necessarily make him as smart as Minato.
I don't know the specific name of the Minato manga off the top of my head. It could be related to a particular genre or have some distinctive features that might help identify it.
If Minato survived, it might lead to a power balance shift in the ninja world. His presence could prevent some of the later conflicts or handle them differently. Also, his relationship with his family and friends would evolve in interesting directions.
Sorry, I don't have that information. Usually, such release dates are made public closer to the actual release time. Keep tabs on relevant manga news websites or forums for the most current details.