Changing the volume increases the area that the molecules collide with so the force is spread over a larger area.
The given above pretty much states already that with the presence of the calcium carbonate which acts as the buffer will allow the solution to withstand changes in acidity. The greater the amount, the higher chances that it will be able to withstand the said changes. Therefore, if Lake X had greater ppm of CaCO3 then, it will be able to withstand greater amount of acid rain.
I'm going to say about 1-2 hours until it will completely dry. It depends on the material of the clothing.
They cause most of their damage when they reach land
