If you have access to M20, that will be the best place to get the basic rundowns of everything that you're looking for. I only kind of understand it and I don't feel like I run it particularly well but it's probably my favorite setting in fiction and almost certainly my favorite RPG. Get a few PCs with Spirit magic and next thing you know you're trying to work out the social motivations of an embodiment of the English appreciation of boiled meats. The conceptual realms of the High Umbra alone are enough for an entire game line. Running mage games is absurdly challenging even without the symbolic abstraction of the greater Mage cosmology. Just developing the ability to shift into a perspective that genuinely believes in its wacky trappings with the iron conviction of fanaticism is not an easy trick. Understanding a mage's paradigm is almost creating a magic system from scratch - everything has to happen for reasons that make causal sense inside the structure. Spend a lot of time thinking about paradigm and recognize that by most medical definitions mages are all insane - their view of the world contradicts evidence available to (almost) everyone else. Read the book in order, then read it out-of-order, then spend a while researching real occult traditions (there are good recommended readings in most of the M:tAsc materials), then try to write some character concepts. You almost have to play it badly for a while to understand the shape of the game, at least without more veteran players to help. The game is insane, possibly unlearnable in an academic sense. To qualify, I've spent a not-insignificant part of my adult life - over two decades - playing M:tAsc on-and-off, mostly as an ST but also as a player.