What is perfect contrition?
The thing that makes contrition perfect is the motive: Love of God.
IOW, fear of the fire of hell is a perfectly good, although lesser, motive, but if the sorrow flows purely from the love of God and sorrow/horror at having offended the Him, it can be styled perfect.
Does a perfect contrition take away the need for Confession?
No, it does not, provided one lives to go to Confession and wishes to receive any of the other sacraments. To "legally re-enter" the sacramental system, so to speak, one must reenter via the lawfully-established gateway: Confession. Apart from a revelation from God, one cannot even be certain that his contrition is perfect or that an act of perfect contrition has cleansed his soul.