Imposing questions Bill, but when you think about it, all aircraft parts were treated to a coat of chromate in the building progressed, even the internal wing structures were sprayed before assembly, so yes the interior fuselage walls would have been sprayed, it's just the bits added by the Soviets that would be a silver grey.
As for armour plating, well your guess is as good as mine, if they wanted a fast light manoeuvrable aircraft with no armament, it's likely the armour plating would have gone as well.