Connections between Painted World of Ariandel and Ariamis?

I got many questions fluttering in my head like:

Why the painting is named after Ariandel? From what I understood, he's just a keeper of that world that he should have burned if Friede didn't stop him. I just found it strange, I've always thought Ariandel was the author of the painting, and that he was called Ariamis ages ago, but now I'm even more wondering who is Ariamis then...

Why Ariandel blood can stop the flame from burning the painted world?

The painter girl created both the paintings of Ariandel and Ariamis? That can't be, since she can't make paintings in the real world from the inside the painted world. So IDK who is her really. If you kill her you get any extra hint?

Why you have to burn the painting? I didn't remember to have such goal in DS1 while going through painting of ariamis, nor I remember to have actually burned the world at the end.

What's the purpose of these paintings? Escape from the rotten world, so that even if the flame fades away forever, you keep staying alive in the world inside the painting? But for some reason the world of the painting must be destroyed every once in a while with flame (I didn't get why they try to replicate the same same cycle thing of the real world with relinking the flame).