The separation of the Hulk and Banner varies in Marvel comics. Sometimes, external forces or internal conflicts cause them to split, but it's not a consistent occurrence throughout all comics.
No. Marvel Comics is a family - friendly entertainment medium for the most part and does not include such inappropriate content related to sexual stories about its characters like Hulk.
Yes, there are some hints of a special relationship between them. In the movies and comics, they share a unique bond. Hulk seems to have a certain level of protectiveness towards Black Widow, and she is one of the few who can somewhat reach out to the Hulk within Bruce Banner.
Well, it could be. But often, even if inspired by real life, there are likely embellishments or alterations made for narrative purposes. You'd need to look into the author's notes or research about it to be sure.
It's hard to say for sure. Maestro could be inspired by real life but might have been embellished or changed for dramatic effect. It could also be completely made up.