As for stacking programs I use ZM combine. Its free, a bit oldfashioned and creates splendid pictures.
I also have Helicon focus, that is not free, it is much more advanced and can control the camera and calculate the number of frames.
But I do not use it, its too complicated and ZM combine is good enough. That is because I have stacked so many times that I have a good feeling for how many frames and what distance to photograph from.