What was the first Russian jet designed with the use of area rule?
Hard to say with any certainty, but Tu-16 and Tu-95 carry obvious signs of application of the area rule. Both had first flight in 1952, which makes it earlier than the Whitcomb's publication.

Whitcomb may have discovered the rule independently, but Germans knew it since 1940s, so my guess is that the Russians either found it from them (lots of very valuable aerodynamic research data was captured after the war), or developed independently (Russians had/have their own NACA, after all).