>so it seems to me that (&arr + 1) dereferences the pointer to the array
It doesn't. Because an array is already a pointer, in (&arr + 1) &arr is a pointer to a pointer (ie, a handle) so *(&arr) is dereferencing the handle to the pointer. So it's still one pointer level deep - it doesn't dereference it completely.
It doesn't matter what it is a pointer to, type-wise. It is still a pointer one-past-the-end, and it is being dereferenced.
Also, &arr is not a pointer to a pointer. It's a pointer to an array. Specifically, its type is int(* )[5] in this example, and so when you dereference it, the result is of type int[5]. So if you do e.g. sizeof(* &arr + 1), you'll get 5 * sizeof(int).
