If Perospero was able of crossing the waterfall with his candy he certainely had the means of doing it from the start and of using his power to allow the Queen Mama Chanter of entering Wano too and that just after the first attempt of crossing that was foiled by King.
Oda is just being too convenient in his writing again.
I'm sure, worst case scenario, he can make his staircase from the bottom of the waterfall to the top then remake his Candy Slug to ferry everyone to Onigashima. Perospero's being nerfed by the plot, I guess. I have no idea why he's on a solo mission, but it's promising. It means he'll get special attention.
thats just a panel? why would luffy wont be able to slam her? its a fight of course both gets their share amount of hits. What matters is shes obviously brushed it off and fight again till the last moment when Ulti had Luffy on her palms, Luffy was about to activate G4 but Yamato came last minute.