Answer to the questions

Method A – image 1 was taken at an aperture of F2.8, and the shot was taken very close to the subject – about 200mm and with a high magnification.  In this situation the depth of field is very small, and it took 36 stacked shots to get the image. (Note that some of those shot would have duplicated certain focus points.  Such is the nature of handheld shots where the camera is being moved to assemble all the required focal points). 

Method A – image 2 was taken at an aperture of F5.6 and the shot was taken from about 1000mm away from the subject but with a lower magnification.  In this situation, the depth of field is greater and fewer shots were needed to assemble a stacked image.

The second shot was taken using ambient light.  And this pushed the ISO a little higher than is ideal – 800.  The first shot was illuminated by flash and this kept the ISO lower at 100.  As a result, there is slightly less noise in the first shot and a slightly better photo ensued. Refer back to the section on depth of field in the “Photographic Basics” section.

Refer to the diagram below as a reminder of the relationship between F number and the depth of field.