Physical property is the characteristic that can be observed, using the five sense, without changing or trying to change the composition of the substance. Chemical property on the other hand is a characteristic of how the substance reacts. It can not be observed without changing the substance into something else. A physical change is a change in which the form or appearance of matter changes, but not its composition.
The first option for 1 and the second option for 2
You can use the volume displacement method. If you had the alligator in a tank and you knew how much the volume of water in the tank was before the alligator was in there you could subtract that from the volume of the water with the alligator in the tank.
