Generally, there isn't a notable amount of Gwen porn comics. The comic industry mainly focuses on providing entertainment within legal and ethical boundaries, and pornographic content is not a typical part of it.
Obviously, Ben could be the one to save Gwen. With his Omnitrix, he has all kinds of powers at his disposal to take on Kevin and rescue Gwen. He knows both of them well, so he would be highly motivated to stop Kevin and bring Gwen back safely.
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.