The main differences are in their expressions and some minor details of personality. In the manga, Deku might seem a bit more intense, while in the anime, he's sometimes presented a bit softer.
I'm not entirely sure as the description is rather unclear. It could potentially be about a character named Issei in the 'DxD' universe and some sort of action related to a fanfiction about him. Maybe it's about exploring or creating a fan - made story where Issei is involved in a stroking action, though without more context it's hard to be specific.
Deku might be completely shocked at first. Since Bakugou has always been so aggressive towards him, he would never expect such a confession. He might just stand there, mouth agape, not knowing what to say.
His friends could come to the rescue. Bakugo, for instance, might use his explosive power to break into Toga's hideout. He's always been competitive with Deku, but he also cares about him deeply.
In 'deku meets future deku fanfiction', perhaps the future Deku warns the present one about upcoming threats. He could tell him about villains he'll face in the future and how to defeat them. This would give the present Deku an edge in his battles and also in his growth as a hero.
Well, obviously Deku in two forms - the younger and the older version are the main characters. The younger Deku is the one who is still growing and learning, while the older Deku has more experience.
As of now, Deku is very much alive in the manga. The plot hasn't reached a point where he meets such a fate. Usually, main characters like Deku have significant story arcs and aren't easily killed off.
It could be his fellow team members. They might betray him out of greed for power. Maybe they thought that by getting rid of Issei, they could gain more resources or a higher position within their group.
Issei could react with anger. He might lash out at his partner and the person they cheated with. He could also become very confrontational, demanding explanations and apologies.