There's also the story of Steve's first real mission as Captain America. He was sent on a USO tour at first, but when he got the chance to fight in the real battle, he showed his true courage. He didn't care about the danger and just wanted to do his part to save his comrades and fight against the bad guys.
One idea could be a story where Captain America and Captain Marvel team up to face a new cosmic threat that's headed towards Earth. They have to combine their unique skills, with Captain America's strategic mind and combat experience on the ground, and Captain Marvel's incredible cosmic powers in space battles.
He could also meet Odin. Odin might view Captain America as an interesting mortal from Midgard and might have some words of wisdom or a task for him to complete during his stay in Asgard.
Sure. In the comics, after Steve Rogers was believed to be lost or incapacitated, characters like Bucky Barnes and Sam Wilson have taken up the mantle of Captain America at different points.
There has been. Different story arcs in the comics have seen new individuals stepping up as Captain America, each with their unique traits and motivations.
In the traditional comic storylines, Captain America is not shown to be bi. His relationships have mainly been with women and there's no indication of him being attracted to both genders.