10 years old Die hard Gold

Good battery acid is about 35% sulfuric acid. Used in drain cleaners at 80-90%. I'd pick your worst drain and use it. I never did it, so not sure how the reaction will compare, I would take same precautions. Ventilate ,cover drain etc... I have used the heavy duty drain cleaner, which will boil, spit, make nasty gas etc. and should not put it in a septic tank could screw up the bacteria.
Yes it can be neutralized with baking soda.
At the warehouse, our battery room drains filtered through a pit of limestone so no separate washdown area was needed. That was only intended for washdown and minor overflows though. Not dumping. For a direct spill we usually threw baking soda on it. If