As generally known, BER is NOT a calcium deficiency in the soil. It is an inability of the plant to move calcium from the soil to the fruit. This is due mostly to temperature swings and inconsistent watering; too much and then not enough. This cycle happens early in the growing season and as things even out the BER usually goes away. Some varieties in some areas tend to be affected by BER, a condition not a disease, more than others. Black Krim in my area is one of those. An inch of rainfall or watering per week is plenty.
Unless you have a soil test indicating a calcium deficiency adding eggshells, tums, milk or any form of calcium will not help anything....unless doing so gives you peace of mind.
The leaf curl looks like a mid-afternoon normal defense against heat or sun or both. If the leaves are crispy that's another situation which may mean the plant is too dry or something else entirely. Usually crispy leaves are also turning brown on the edges which I do not see on your photo. Your leaves look healthy, just curled a bit. If by chance this gets worse or involves the entire top portion of the plant, it may indicate an herbicide drift. Take a photo of the whole plant if this continues.