Android by default is also swipe swipe swipe. You need to tweak the settings to get the older and saner 3-button setup back.

As far as the Back button, on iOS the norm is for it to be present somewhere in the UI of the app in any context where there's a "back" to go to. For cross-app switching, there's an OS-supplied Back button in the status bar on top, again, showing only when it's relevant (admittedly it's very tiny and easy to miss). Having two might sound complicated but tbh I rather prefer it that way because in Android it can sometimes be confusing as to what the single global Back button will do in any given case (i.e. whether it'll navigate within the current app, or switch you back to the previous app).