FIRST, I ask that you pray and ask for guidance. God can give you a clearer idea than anyone here or anywhere else.
Baptism is essential for Salvation, but not in the way most people think. Water baptism is an outward ritual while baptism by the Holy Spirit is something that MUST happen for you to be saved. The Greek of the New Testament makes specific delineations between water baptism and spiritual baptism, which are all translated as one word: baptism.
As for the ritual of water baptism, this is again an outward expression of an inward choice. The mode of water baptism is totally one of choice. Whether it is total submersion in water or a sprinkling on the head, is simply a matter of choice and both modes have references in the Bible. The ritual does not matter, the commitment to Christ and confession that He is Lord is what counts.
As for the absolute need for baptism, here is some scripture:
Mark 16:16
He that believeth and is baptized shall be saved; but he that believeth not shall be damned.
1 Peter 3:21:
21and this water symbolizes baptism that now saves you also--not the removal of dirt from the body but the pledge[5] of a good conscience toward God. It saves you by the resurrection of Jesus Christ,
Matthew 3:11:
I [John the Baptist] baptize with water those who turn from their sins and turn to God But someone is coming soon who is far greater than I am – so much greater that I am not even worthy to be his slave. He will baptize you with the Holy Spirit and with fire.
Romans 10
9That if you confess with your mouth, "Jesus is Lord," and believe in your heart that God raised him from the dead, you will be saved. 10For it is with your heart that you believe and are justified, and it is with your mouth that you confess and are saved.
1 Samuel 16:7
for the Lord seeth not as man seeth; for man looketh on the outward appearance, but the Lord looketh on the heart.
Good references:
www.biblegateway.com - for scripture lookup and boolean searches
http://www.rr-bb.com/index.php?s= - a pretty good and active forum I have found for religious discussion
I hope this helps. God bless
Dave