The laver basically means round. It was round at the top and round at the bottom. Running water was a must as it could not be stagnant water.
The sacrifice was already made by the time the laver was used. One must be prepared by using the laver before going into the presence of God. We must all prepare to meet God. We should all stop and think about who God is and if we are preparing ourselves to go before Him.
There was life in the water. God told Moses to strike a rock and water began to run to give life to those that were thirsty. The lady at the well was told that Jesus Christ can provide a water that a person would never thirst again. There is also a fountain of water that flows from under Christ's throne.
There are things that we touch, that we see, that we involve ourselves in that are of the world that should be purged of. Imagine the priest standing at the laver, rubbing and searching, rubbing and searching just to make sure that he was clean before God. God said that if the priest was not clean prior to coming before Him that he would be struck dead.
There are things that we do on a daily basis are likely many sinful things. This is because we are of the flesh and the flesh is sinful.
James 4:8 we should draw closer to God BUT we should cleans our hands (sins, repent) before doing so. If you're a Christian and are having a problem getting your prayers thru to God, make sure your life is cleansed from sin. God will not hear you if you're in sin because He can see/hear over the sin. Ephesians 5:26 Christ gave Himself to the church but He is the water that washes away and removes our sins. Once we are saved, all of our sins on the inside are forgiven and removed forever BUT the outward flesh is sinful and should be cleaned often.