Starting at DF on top, I would go:5 4 3 4 3 5 4 3 4 3 4 3 53 2-2 1 2 1 2 1 2-2 1 2 1
Thank you, m1469!
Why not use 5 and 1 at the top too, in an analagous way to the rest? I think it gives more control and physical stability. Personally I'd favour it over 53 in just about any instance where it's physically possible to use it.
2) The main reason to use 1 in the other cases is because that's what's already sitting there within the descent when using the fingering given.