Chakra = stamina...... no chakra = no strength.. the moment he started molding chakra, his body started relying on chakra. If he attacks, he wastes chakra.. why? Because chakra is dependent on stamina also.
On top of that he has bloody tentacles which is a jutsu on its own.. which requires the usage of chakra...
Ay V2.. manga doesn't say he uses infused strength.. logic says, he does.
No, you will waste your chakra via using your strength/speed.. anything a ninja does requires chakra. Physical energy that is used for strength is part of chakra.
Only difference is people like Sakura can control that chakra on a scale others can't.