I live on frozen apple purée and frozen baked apples in the winter. Well at least for desserts anyway.
No, as you can see it works for me.
Picked ours last week, ripe too. As suggested, purée and freeze for winter use or if unbruised by the fall, core, fill with dried fruit and syrup and bake in the oven. Then freeze for winter use.
They needs food. They needs sun. They needs planting with the top of the 'bulb' no more than an inch below the soil level. So, yes move them to a better position.
Now called Ageratina altissima 'Chocolate':
Probably not getting enough food to flower.
The leaves on P. obovata are more rounded than the ones on this to my mind.
P:. rockii is a possibility.
No-one live near us, we are very isolated here.
Pity you don't live near me, you could have plants of various forms of G. rivale for the asking.
If you keep it dead headed then they are not root invasive like some things. They will seed around and yes they are promiscuous, so there are lots of new named things around. Many of them not much different from each other.