1) Should we still be using oil annointings today in the Body?Yes. I think a lot of people are saying "No" here because most protestants don't have a sacramental worldview like Catholics do. Catholics firmly believe that God can bless us and protect us through the things of this world: water, oil, bread, wine, laying on of hands, etc.
2) What do we use it for?Catholics use it for the administration of the Sacraments and the blessing of objects. Persons are anointed with oil by the priest during Baptism, Confirmation, and Anointing of the Sick.
3) Do I annoint my wife, kids, and my doorposts, or is that just out in left field somewhere?Well, for ordinary circumstances like this, Catholics usually use holy water instead of oil.
After I had a conversation with a person who was possessed (or, at least, tormented) by a demon, I put holy water on my thumb and made the sign of the cross on my door posts, my window frame, and the headboard of my bed. Parents often bless their children this way, by putting holy water on their thumb and making the sign of the cross on their child's forehead. In a Catholic home, you may also see small holy water fonts on the wall by the front door. That way a person can bless themselves when they go out into and return from the world.
I hope that helps. For more on holy oils, go here and here. For more on holy water, go here and here. For more on blessing objects and/or persons, go here. For more on sacramentalism, go here.
Heb 1:9 Thou hast loved righteousness and hated lawlessness; therefore God, thy God, has anointed thee with the oil of gladness beyond thy comrades.