Yes, that whole area is open behind the upper firewall panel.
That rust is quite common from leaves, or worse, pine needles, collecting in the cowl.
The good news is those rust holes don't cause water to get in the interior, unlike the B and E cars where the rot is usually on the inside panel.
I would clean off as much of the rust as practical. Back up the larger holes with some fine metal screen, then fill over the holes with long strand Tiger Hair. That repair will last a long time on a car that doesn't see much wet weather.
Jeff
