Re: What other supporting characters would you like to see?
Hercules, at least Marvel's version of Hercules, would he interesting. Given that the MCU Thor has elements of Hercules, maybe the MCU Hercules should have elements of Thor.
Best I can think of are Herc not quite being the brainless bruiser he appears to be. He can say things like "Odysseus was one of my best friends." "Don't play chess with me, I helped invent it." "Beware of Greeks bearing gifts, especially big wooden horse gifts."