Welcome, gandarloda, I have been greatly anticipating your case history, because I recall that you have been a member of the Jhana Support Group for a long time. So, welcome, and thank-you.
Like you and Michael I too had many special and recurring "dreams" as a child, which I now recognize were OOBEs and/or past life recollections. As an adult I had a lot of deeply frightening dreams about snakes, they were mostly through my thirties. Eventually I got through my deepest fears, and therefore no longer have frightening dreams.
It is interesting to note that you saw a purple snake. I saw a pink one. The significance of the pink snake to me was I used to live in a tropical island called "Trinidad." There they have one of the most poisonous snakes known. It is in the coral snake family and it is pink. While body surfing there as an adolescent one floated past me. I almost died from fear. When I could recover rational thought I saw that the snake was dead, and recalled the snake is not aquatic.
Good to know that you have both light and sound attainment, which is mentioned in the suttas. I too have it. They are of special interest in Sikh mysticism. If we were Sikhs we would be considered meditation masters. But, as Buddhist laity, I am disrespected by laity and priest alike.
I too experience the energy channels that you described. They are called 'nadi' in Sanskrit and they are the meridians of acupuncture. I have found I can move that energy around when I need to for health. I mean that when my health declines I see that one or more meridians have shifted, so I go into deep meditation and move them around, then health is restored.