Yes, and Sasuke's Chidori is not one of those things.It was put on par with Gaara's defense, so anything it blocked Neji;s rotation can as well.
So what's stopping Neji form immediately expelling more Chakra to replace the pierced parts?
Agree, but if the spinning is strong enough, that metal can be broken. Neji's rotation has the possibility of being able to damage Sasuke's arm if he attempts to attack Rotation head on with it and even if you believe Sasuke could pierce through Rotation, that isn't a possibility you can deny.
Nothing, but that doesn't help like I just explained. That chakra does nothing if it's not spinning. If Neji has been hit w/ Chidori he won't be spinning.
Yeah, "if" the spinning is strong enough. But if it was strong enough then Chidori wouldn't rip through Rotation, it would be repelled. Just how the metal pole wouldn't stop the wheel if the spinning were strong enough. However there is more evidence leaning towards Chidori piercing Rotation thus there shouldn't be any discussion on whether or not Sasuke takes damage.