Answer 1

Data encapsulation means you keep the variables strictly to its own class. For example, if you have a Car class with an engineBrand string variable, you want a Driver class to use the car but can't modify this.
Encapsulation, on the other hand, allows you to keep methods "as they are". So you can extends ie. a Engine interface with a StartEngine function, and each Car, Plane, Ship, which implement this interface, can StartEngine, no matter what it does.
Think Encapsulation as a black box, with (optional) inputs and outputs. You only need to focus on this inputs and outputs, the rest is done by the methods