One great New Vegas independent Vegas fan fiction is 'The Courier's Redemption'. It follows the courier's journey after the main events of the game, exploring their moral choices further. Another is 'Vegas Under Siege' which creates a new threat to the city and shows how the characters from the game deal with it. There's also 'A New Dawn in New Vegas' that focuses on rebuilding the city in a unique way.
I'm not aware of any so - called 'famous crazy vegas sex stories' that are appropriate to share in detail. Vegas is known for its entertainment, gambling, and nightlife, but focusing on inappropriate stories isn't the best way to represent the city.
The main distinction of porn with a story genre from regular porn is the presence of a coherent narrative. Regular porn often jumps straight to the sexual action, while the story genre tries to add some kind of story framework around it. But in the end, both are adult-oriented and feature explicit sexual content.
Well, it's hard to say for sure. The concept of 'porn-like' is quite subjective. Some might consider certain novels with excessive sexual descriptions as such, but it depends on individual perspectives and cultural standards.
In many places, 18+ porn comics are considered illegal. This is because they can have a negative impact on society and violate moral and legal standards.