1. When you open the statistics, that in itself creates another avastUI.exe occurrence, in some cases two additional entries may be created, depending on how many UI windows you have open. Real Time stats are going to be quite busy.
One instance of avastUI.exe reports 25% on my task manager (but t isn't impacting my system) and that no doubt is the Statistics window. And yes it does slowly creep up, currently 30%. But this in itself shouldn't be much concern. I generally don't use the Statistics option as I find the information there rather lacking in useful data and I don't keep it open if I do use it.
4. This scan bar has been like this for some considerable time as the scale for the numbers is way off.