In the case of those illnesses, that really has more to do with general hygiene and changing/washing masks than how you take them on and off. As for self infection, again, the average cloth mask isn't really stopping infection if there's a high airborne load, so if the mask is saturated, it's either too late or it's because you loaded with virus, in which case, it doesn't matter how much you touch it.1. Unless you stop someone in their car and ask them, you have no idea where they donned it or how many stops they're making. You don't need to don it at home, you don't need to doth it at home. You need to don before the first time you need it and after the last location.
2. Not sure what your question is. I didn't mention protection when discussing auto-infection. If you wear a mask in 3 or 4 stores, there's a possibility that mask has captured infectious material, from your own mouth or from the environment. In extreme cases, as zrickety has inadvertly pointed out, people not wearing or caring for masks correctly can end up with bronchitis, pneumonia, and other infections.