Ahh, yes, laying on of hands. It seems to me that the laying on of hands is a crucial thing in the First Church, one only needs to read Acts to find that out. Jesus laid hands on people to heal, so did the Apostles. It's also found all throughout the Old Testament, especially with Moses (Deu. 34:9).
The hands are sort of the instrument God has chosen for the usage and transference of the Holy Spirit. As well as they are used by God for designation (i.e., to a ministry).
The Apostles (and every follower of Him) were given authority to lay hands on the sick to heal them (Mark 16:18, Acts 28:8). God used the Apostles to also give a person the Holy Spirit (it signified Jesus' power and control, actually, in the Apostles) by the laying on of hands (Acts 8:17), something we don't see much anymore, do we?
Luke says that "God wrought special miracles by the [u]hands[/u] of Paul" (Acts 19:11).
Paul instructs us in First Timothy 5:22 to "Lay hands suddenly on no man, neither be partaker of other men's sins: keep thyself pure." This is most likely referring to appointing any person to a sacred ministry, but could also be took as laying of hands in general. We must follow the Spirit. This is a very important issue. If you declare a person who is resisting the Spirit into a position that they should not have, you will be in serious, very serious, error. This, Paul was instructing Timothy, because just because a person seems 'pious' and has all the right 'doctrines' doesn't mean their fit for the ministry, they must have 'proven' themselves through time.
You do not need to lay on of hands though to cast out an unclean spirit or heal, as Philip the Evangelist, when he preached the unclean spirits came out of the listeners as he preached and they were healed (Acts 8:5-7).
So it seems we can glean from Scripture that the laying on of hands is vital. The laying on of hands for healing and casting out of demons is for every believer, too, that is mature in the Spirit and is walking with God and being a witness unto Him. But we also know that as the Word is being preached, unclean spirits can and should leave people who repent.
It's a fascinating subject.