Driving a block or two with the parking brake on is likely to generate some heat and cause some wear but unlikely to do any real damage to your braking system. When I go to the gas station, I notice little signs that say I shouldn't top off the tank. Topping off most likely will not damage your vehicle, but it may add to air pollution. Topping off, especially to the point of having gas trickle down the side of the vehicle, allows more gasoline vapor to escape into the air. It may not seem like much, but the pollution from a little raw gasoline adds to the air when it evaporates is considerable worse that would come from the same volume of gasoline if it went through the car's engine.
Most cars have a vapor recovery system as part of the pollution control equipment.
Is uses a canister of activated charcoal to capture gasoline vapor that is emitted in the car's fuel system. Eventually, it sends the vapor to the engine. Topping off can make it difficult for the recovery system to work effectively.