Come Passover I make everything by hand, including grinding the hand made matzo for the matzo balls. And then I'll use home made schmaltz without any doubt. However, I do not agree with overnight refrigeration. I do not see a point for that. 15-20 minutes is plenty and when I do not have time, i.e. Passover (there is whole bunch of time constrains) I’d do it without refrigerating them at all and they work fine. They are always soft. Very important in my family.
As far as them falling apart, the reason I mention that was because last Sunday I was making some and fallow the recipe to the "t" and they fell apart completely, it was terrible. As far as quantities of ingredients, like I said, I am not really sure. One thing I do know, you can't have too many eggs or they will taste eggy and that is big no-no for me and even more for my wife.
You are what you eat.