Biggest flying (size and weight):
Mi-26 (100-200 passengers depending on the overload factor the pilot accepts
26 000 kg cargo inside or on a hook. firefighting version has a 16 000 liter water container)
i think all those guys can get in this thing whitout overloading it
Biggest flown-a-few-times. this is still the absolute record holder in size and cargo capacity:
Mi-12 (take 2 Mi-6 drivetrains, put them on wings and add the largest fuselage you safely can get in the air with those)
max load: 40 000kg
Previous record-holders:
Size: Mi-6
Cargo: Mi-10