A. But arrancars ARE a type of hollows, they`re essentially a lot of souls merged into one being, i always assumed all the souls would demerge and get purified.
B. I`m pretty certain it works as long as the final hit is done with the sword, remember that the problem with the quincy was? shinigamies purify the hollows, quincy permanently *delete* the hollows existence. Also, the gates of hells open when the hollow itself was evil BEFORE becoming a hollow, everything afterwards get deleted, what`s his name went to hell because he killed that kid`s mom.
C. Well... you got me there.