When Luffy has destroyed Kaido with internal destruction and they shackle him up with seastone then of course they can cut off his head, if so required, to say killing prone unconcious physically destroyed Kaido requires ENMA is retarded.
So established Yonko Kaido was beaten in his own territory and the other yonko didn't capitalize on it, nor the citizens of Wano? By who? The marines don't care to come to Wano, neither did WB, Imu won't dirty his hands, Teach wasn't that powerful. I'm finding it hard to list 5 people he lost to in his current state.
He's been captured 18 times and they never bothered to cut off his limbs? It's PIS either way, and confirmed he was not under Impel Down like conditions. Getting chained by ineffective levels of seastone, or no seastone, or getting jailbreaked while on a minimum security ship by King, the result is the same. This time it is plot relevant so he will be properly imprisoned if he's taken in.
Zoro trash talking means nothing, slicing is his fighting style.
Oden couldn't kill Kaido either, Kaido would have beaten him with hybrid or awakening, this isn't very difficult to see if you know shonen tropes...
No Zoro is not inheriting Oden's will. That is Luffy+ Momo primarily, they are the ones who set up this alliance, Luffy is the one being asked by Kinemon to take down Kaido.