Hit did all those things because of Time Cag hax and even then someone like SSJ2 Kefla would be able to break out of it given her power was even above 2nd Sign Goku (Roshi said if any of her attacks connected Goku would be killed), and Jiren was using a lower power level against Hit then he used...
I don't think Roshi really mastered his max power form until Super, hence why he never uses it in battle just to blow stuff up.
But yes if Roshi shoots a max power KHH straight away and Tao tries to tank it, it would be bad for him.
Yes. As you just said Trunks doesn't know Vegeta has SSJ2 at this point. Was Gohan a SSJ2 against Broly BTW? He didn't have any sparks or bang, though it is stated that he actually trained and got stronger than he was as a kid.
Yeah. Also what's the point in having a God form when Goku was still nowhere near the level of the GoDs? Why couldn't it had been just any generic Super Saiyan form that made Goku stronger?
It would make sense if Goku and Vegeta actually fought gods, that let's say, we're maybe lesser than...