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.
Red Hulk in the comics is General Ross after undergoing some kind of transformation. He's got immense power and is a force to be reckoned with. His appearance and abilities differ from the classic Hulk in several ways.
In comics, the height of the Green Hulk isn't fixed. Sometimes he's shown as being around 8 to 10 feet tall, while in other instances, he might be even larger. It all depends on the creative decisions of the comic creators.
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.