Left-handed children are usually taught right-handed handwriting by people who have never thought about it, and then corrected for the result.
This is the single biggest change and it is free. A right-handed child angles the paper anticlockwise; a left-handed child needs it angled clockwise — the top-right corner tipped up. Almost every classroom sets every desk the same way.
A left-handed writer pushes the pen and their hand covers what they just wrote. Holding roughly a centimetre further back from the tip restores the view, which removes most of the reason the hook develops.
Curling the wrist over the top is what a child does to see past their own hand. Fix the angle and the grip position first; the hook usually eases on its own, and attacking it directly rarely works.
Usually not. Paper angle and grip position do far more than equipment. A smudge-resistant pen can help once a child writes in ink, but it is not where to start.
No. That is not something to do.
Yes, particularly while the child is working out how to see past their own hand. It usually evens out.
Part of our guide to Handwriting & early skills.