Arm & Hammer CLEAN SHOWER REFILL 60OZ

Do you have to wipe or rinse this off?

When you buy the 2 pack for 23.25 do you get a total of 120 ounces

Is this safe for use on acrylic?

Are these a concnetrated strentgh? In other words why is the same 60 oz bottle about $4.25 per bottle at my retail store? (in this case Target)