Barbarossa works like this: on the FIRST round of combat when Germany attacks Russia, German ONLY( NOT AXIS) units get a plus 1 to their attack combat value( ex. A 3-4 German infantry will hit on a 4 or less). Russian units will get a -1 modifier to their defense combat values even if the attacker has only axis minor units ( ex. a 2-3 Russian infantry will defend on a 2 or less) . Air to air combat, German get a -1 to their dice roll, and Russian a +1. Very important to remember: it's only the first round of combat, not a full turn.
Winter rules apply to all AXIS units inside the 1939 Russian borders except mountain and Finnish units. 1939 borders don't include vyborg, eastern Poland or any of the Baltic states. I hope that will help you.