Shield Bash vs. Charge or RP can be explained via lore? I must have missed the part where Brigitte threw the levelled skyscraper back at Doomfist… 
Seriously though, while we have no indication to say Genji has superhuman strength, we have no indication to say he doesn’t either. Cybernetic enhancements could do wonders for his strength or perhaps it could explain why Hanzo has 2 dragons but Genji has 1 as he may channel it’s power through his body.
(EDIT: I should probably specify that it’s not enough to just assume everybody can have superhuman strength then, there has to a reason behind it. In Genji’s case it’s cybernetic enhancements or Dragon magic)
I assume for Rocket Punch, it triggers an electric shock throughout whoever it hits and Genji’s body is probably a better conductor than most others. DF does have an electrical-ish effect surrounding him during it.