Hi selfonlypath, I was the author of the thread you mention, now that I know more, I can tell 1) that tummo awakens the spinal nerve indeed, but 2) the central channel is not the spinal nerve. I posted another thread here
http://www.aypsite.com/plus-forum/index.php?topic=3320 about the subjet.
As for the white and red drops, indian yoga knows them well, but, as many buddhists students don't know anything about highest teachings, we can guess that many yoga students don't know the Yogachudamani Upanishad, mentioned in Satyananda's book :
http://www.eng.vedanta.ru/library/kundalini_tantra/2_bindu_visarga.phpGo to the bottom for "the red and white bindus".
But this is only the beginning. When the 2 bindus are merging, there are many things left to do. I suppose that there are further details in some Upanishads, but I don't know them, for now...
So, indian and tibetan are very close, but few people know the texts which demonstrate it. It took me much time to find them.
Satyananda's book gives a practice to trigger exactly the same thing that tummo is supposed to (now I can say it, because I went far enough in tummo to know it), with different means. But at the end, you find the same things. For example, tummo practice doesn't mention Bindu Visarga or some other points, but I found them anyway, it doesn't mention kundalini, rather "clear light", but kundalini reveals clear light... So, once you've have advanced enough in one system, you can help it with the other one.