Can you give some specific examples? I’m so thoroughly baked into iOS that I don’t notice these potential issues.
Creating folders is the same as iPhone.
There is a caveat that if the icon was held very still then you'll open a menu similar to 3D touch menu. I never use this because it isn't that discoverable.
2. Quitting apps completely (not having them run in a background thread)
I agree about point #1, but I'm also not sure how to make copy/paste particularly obvious with touch. To be fair it's not really obvious with a mouse or other external pointing device -- it's something we just have to learn.