Definitely not. Different places have different laws regarding this. Some countries view such novels as violating public morals and have laws against them. While in other places, they might be considered a form of freedom of expression up to a point, but there are usually still limits like not being sold to minors or being sold in restricted areas only.
Definitely not. In modern literature, we aim to have works that are inclusive, educational, and inspiring. Adult smut stories are not in line with these goals. They can also be offensive to a large number of readers and can have a negative impact on the overall literary environment.
Well, smut manga typically features a lot of sexual imagery and scenarios. Regular manga, on the other hand, can be about anything from superheroes to school life and doesn't focus mainly on sexual themes. The main difference is the emphasis on sexuality in smut manga.
One example could be 'Love Hina'. It has a great story about a young man and his relationships with various female characters in a boarding house. There are some romantic and comical situations that border on the more 'smutty' side at times. The character development and the overall plot of the protagonist trying to find his place and love make it engaging.
The plot itself should be engaging. It can't just be a series of sexual scenes. Take 'Nana' for instance. It has a story about two girls named Nana who are on different paths in life. There are some romantic and passionate relationships in it. The overall plot about their friendship, career aspirations, and love lives holds the story together, and the 'smutty' elements are just part of the bigger picture of the characters' lives.
One way is to stay away from sources that are likely to have such content, like some unregulated websites. Don't actively seek out materials with adult - related inappropriate content.