[ReignOfError]

1) When God says "Go to, let us go down, and there confound their language, that they may not understand one another's speech." who is the 'us' plural;

The "royal We" was the norm for a sovereign in King James' time.

[OneWingedShark]

>>1) When God says “Go to, let us go down, and there confound their language, that they may not understand one another’s speech.” who is the ‘us’ plural;
>
>The “royal We” was the norm for a sovereign in King James’ time.

That does not discount that He may have been using the as-a-group form here, it only acknowledges that this singular form is more likely.
Remember I said a “straightforward reading” meaning making as few assumptions as possible.