Constants never change? Correct?

Answer 1

Yes for sure, but it depends... keep reading:

1- Consider a struct Menu.

struct Menu {
var index = 5
}

let menu: Menu = Menu()

print(menu.index) // will print 5
menu.index = 7 // will throw an error cause menu is a constant.

2- Now consider Menu is a class
class Menu {
var index = 5
}

let menu: Menu = Menu()
print(menu.index) // will print 5 as expected

menu.index = 7
print(menu.index) // will print 7 unlike when Menu was a struct.

It has with value types(structs and enums) and reference type(classes)

Answer 2

Yeap

Answer 3

Correct