i sized up on the apple airpods earbuds and that solved the problem for me of them falling out. The medium seemed to fit well but would fall out, and when i went one size larger, they would generally stay in. I say generally becuase on occassion i find that i have to adjust them, and one thing you can do is to twist them so the shank is actually angled a little forward rather than straight down.
I also have some really nice wired earbuds that penetrate fairly deeply into the ear canal, and they are perfect, but they are wired. So I know what you mean about seeking a better fit.
That said, I find that the features that come with the apple airpods used in conjunction with an iphone to be so amazing, I would go to great lengths to make my airpods work.
No idea about your other question, though.