From what I have found is most of us deal with them in waves. They come and go. I am surprised though that your doc put you on that med, as from what I understand it can make them worse.
I have also heard there is a new beta blocker out there call Bystolic. You may want ot talk to your doc about it. I heard it does not have as bad of side effects.
Hard to say. In my country, they don't use antiarrhythmic drugs against single premature beats, unless there is existing heart disease (except beta blockers).
Maybe your heart rate is getting too slow and you are in better shape? Maybe just a coincidence? I think this will be clearer after you see a cardiologist, it often helps.