Yes. The conflicts between Sanji and Luffy in the manga often stem from complex circumstances and character developments that drive the narrative forward.
One great fanfiction could be about their adventures on a new island not shown in the original story. Maybe they encounter a powerful and strange new enemy. Luffy's determination, Zoro's strength, and Sanji's culinary skills all come into play in this new situation.
Another theme is rivalry. Zoro and Sanji have a friendly rivalry which can be elaborated on in fanfictions. For instance, they might compete in a friendly tournament on the ship to see who is stronger or more useful in a certain situation.
Yes, there might be some. You can try searching on popular fanfiction websites like Archive of Our Own or FanFiction.net. However, the availability can vary greatly depending on how active the 'One Piece' fanfiction community is in writing such stories.
There might be. However, it's important to note that this kind of fanfiction is more of a creative and often not part of the official storyline. Some fans really enjoy exploring this kind of relationship between Zoro and Sanji in their own fictional interpretations. They might add interesting plot twists and character developments to make the kiss scenario seem more believable within the world they create in the fanfiction.
Often, they involve a lot of emotional build - up. Since Zoro and Sanji have a complex relationship in the original story, in fanfiction, the kiss might be a result of resolving their differences or a sudden realization of deeper feelings.
I think it might have been a character introduced to add depth to Sanji's backstory and motivations. But without more context, it's hard to say for sure.