Callen, yes, there are bloodline spells and there are instant ritual spells. It's not a bloodline spell and it's not an instant spell (if it were, it wouldn't cause continuing warping and couldn't "break").
Callen, it's not A+B = 1. It's one season = Longevity ritual + unique lab text, and this is not reversible as a logic statement is (1 = A+B which is equal to A = 1-B). With the season you get a lab text you can use to "dodge the work" but the work has to have been done.
They (the lab activities) are limited that way. MT2 will always equal or exceed zero, it's true. And if you managed to use viz in the creation of the ritual spells, that would be limited by MT2.
Yes, it would be a lab activity, except AM(p. 101) says it is not. Notice it does not say the spell must be repeated, rather "the focus must be repeated". What does "focus" mean in this context? The second paragraph of the Longevity ritual section explains "The Longevity Ritual creates a magical anchor, sustaining the vital life force of the magus, often by directly affecting the tissues of the magus's body. This anchor, however, prevents the magus from expending his life force in normal human fashion, so the magnus becomes permanently sterile. The ritual takes a season, and culminates in some sort of focus, which is appropriate to the magus in question. (Stuff, stuff, stuff.) The focus is always something which can be repeated, and does not require continuing actions or the possession of an object." This says to me that the "Longevity ritual" "enchants" the body much like enchanting a magic item. The anchor is permanent, and the sterility is permanent. Thus, the first season is a lab activity. But, perhaps, to an error in the Order's understanding of magic, the Longevity ritual is imperfect and the body can become detached, causing you to begin aging again (but not, note, become fertile again, for the anchor still exists within the magus). Attaching the body of the magus back to the anchor is a simple matter, requiring only the lab text of the original enchantment and vis. This is not a lab activity unless you wish to wish to improve the enchantment. That would require a season in the lab, and the creation of a new anchor. Ritual, I think, was a poor choice of words. This is something singular, which is why it gets it's own section. Given how the game has gone, I would call it the Longevity mystery, which I think, is closest to what is going on.