Hello Katara,
The soul that passes from this life to the next(The soul) is a complete being -----------all of you and all your knowledge gained on this plane of exstence but now vibrating at a higher rate.The soul is still ALL of you.
It is not a good idea to try to contact people who have passed over.They are now trying to move on with a new life.Yes it possible and can be done by a good medim or psychic.The choice to do so is personal and up to the individual.
Light and grace.
Eternity.