Sure, She-Hulk is related to Hulk. Jennifer Walters, aka She-Hulk, got her powers because of a blood transfusion from her cousin Bruce Banner, who is Hulk. This connection is a key part of their storylines in the comics.
Captain America would be a great addition. His leadership and moral compass could guide Hulk and She - Hulk when they face difficult decisions. And his combat skills could come in handy during battles.
In many comic versions, She-Hulk gets her powers after being exposed to gamma radiation, similar to the Hulk. But the details and circumstances can differ in different story arcs. Sometimes it's due to a scientific experiment gone wrong, or a deliberate attempt to gain powers.
She-Hulk became She-Hulk because of a unique set of circumstances. Bruce Banner's blood, with its gamma radiation, entered her system during a medical emergency, and that's what caused her to turn into She-Hulk. This event changed her life forever.
She - Hulk has many great stories in the comics. For example, her struggle to balance her normal life and her superhero identity. She often has to deal with the legal world during the day and fight villains at night. This duality makes for some really engaging plotlines.
Comics usually depict Hulk as stronger than She-Hulk. Hulk's strength levels are often at a much higher magnitude, but it doesn't mean She-Hulk is weak by any means. She has her moments and skills that contribute to her being a significant character in the comic universe.