Of all your ideas the homescreen is most in need of a facelift and this can be solved by just letting us turn off the floating-to-the-top icons.

What iOS needs is some deep UX changes. I reckon most dropped iPhones are caused by people over reaching when using their phone one-handed (ie the way it was designed)

All interactions should be within the bottom two-thirds of the screen of the regular iPhone and the bottom third of a Max model. The bottom-up notifications is a good start.

I would redesign the multitasking view so that when it was invoked I had the usual set of cards to leaf through but the RH card would be control centre. The bottom part of the screen where the dock normally lives would be a compressed stack of notifications that expanded when touched.

On the lockscreen the current camera gesture would bring up control centre. There is already a button for the camera shortcut.

There would be zero interactions that required the top-third of the display. I would adopt the universal back gesture from Android.