Previous answers did not satisfy me so I tried to look into the matter more thoroughly, asking a few friends who are in the know and trying to cite sources that clarify things as much as possible. Of particular help was Antonios “Rave-n” Galatis, co-developer in the making of M20, who helped me put all this together as clear and well-defined as possible.
For starters let’s clarify a few things:
As a Mage you can Meditate near a Node to
… refresh your Quintessence Rating…
(M20 -Meditation p.281)
(Quintessence Rating being equal to your Avatar Background)
The process of of drawing Quint. from a source (Node/Tass/etc) is also called “Channeling” (M20 – How Do You DO That, ‘Channeling Quintessence’ p.43) and, evidently, does not decrease/drain the actual Node’s reserve.
This particular method via Meditation is simply your own Avatar refreshing its full potency, its natural energy reserves (M20 – Quintessence p.332). Furthermore, both in the latter and in (M20 – How Do You DO That, ‘The Basics’ p.42) it is made clear that you can Channel more Quintessence into your Pattern than that Rating through a Prime 1 Effect. Essentially, we come to the result that
– (Mages have a “default” amount of Quintessence in their pattern which depends on the potency of their Avatar (as per the relevant trait)
It should also be mentioned that “Channeling” actually has a somewhat broader meaning which, usually, meaning with “moving” Quintessence from a source to a recipient, as the previous sources mention.
So, to answer the actual items the question consists of:
Prime1 states that without it “a mage can’t absorb Quint. beyond their Avatar Rating. Does that mean the previous limit is no longer relevant or something else?
Yes. A Prime 1 Effect indeed allows you to gain (and store) more Quintessence than your Quintessence/Avatar Rating from a Node. However, that Rating “limit” still remains relevant because it’s the natural “energy baseline” you replenish your reserves to when Meditating at a Node, as described above. Furthermore the Avatar/Quintessence Rating defines *Note: In spite of the general “Rank 1 = Perception” paradigm of Sphere Effects, this seems rather certain due to having 2 sources, mentioned above.*
Prime1 also states you can “perceive and channel Quintessence from Nodes/Tass/Wonders”. Can’t you already get Quint. from Nodes via Meditating (the Skill) on them? Does this represent another way to do the same, possibly in less time or does “channelling” imply manipulation of Quintessence without absorbing it into your Pattern?
See previous element. Moreover, the “Tass/Wonders” part of the text seems to imply the overall possibilities in studying the Prime Sphere so it’s a bit confusing. Which brings us to…
Prime3, the one which causes the most confusion, states that with it you can “draw both free and raw quint from Nodes/Tass/Junctures etc”. This directly correlates with the previous point as they appear, at least, to have some common ground, which seems irregular given their different level. What does each one do?
We can conclude that Prime 3 is the required rank to Channel from Tass/Wonders/Junctures and, probably every non-Node source, into Effects or Patterns(including your own). This deduction comes from the both the very description of the Rank and a relevant table in Common Magickal Effects (M20 – ‘Quintessence Quintessence Energy’ p.510), where ‘Absorb’ probably means to Channel into yourself.
Also, something that should be mentioned is that if a Mage simply wishes to use the Quintessence reserves in a Tass, they don’t need to roll for an Effect if the Tass is on their person, and even if it is at a distance a Prime 2 roll suffices. That part is verified by (M20 – How Do You DO That, ‘Accessing Tass or Periapt Quintessence’ p.45)