Apple’s Cocoa text system is a complicated beast, but also extremely flexible, and with a bit of work, it can be molded to match many working styles. This how-to covers the 2 major ways of customizing the text input system: Default key bindings, and for still more control, input managers.
This is fundamental knowledge for Mac users who type on keyboards. With luck many of the default rules apply to iOS as well.
I have been using the Emacs key-bindings since 1975…