Welcome!
There are no stupid questions (but those are always the easiest to answer).
And not every "similar" question is asking for the same responses. But only from reading several such threads can one get a "consensus" - that, and there is something to be said for avoiding repetition etc. Additional insight may be gained if you read/skim these:
Just curious - what other games are you considering? How would you characterize your group? Action-oriented? Puzzle solvers? Power gamers? Dramatists? (Nothing wrong with any style, it's just that diff styles would call for diff responses.)
+1
As SG, you can have read some of the supplements without the Players needing to worry about them. Just be reasonable and generous as to what "the Characters" would know vs. "the Players" - some obvious advantages shouldn't be a surprise/secret in-character, and others might not be fully understood by any but the most veteran scholar. 
(And that's where something like Mysteries or one of the ROP books can be brought in "later" in the saga if/as that plot element becomes exposed.)
And that also can be one of the problems with it - to have a starting character that custom builds a Mystery for themselves is not to every SG's taste.
Some of the rules and "bloat" can be used as an in-game reward, a "treasure" that is found - or that can be pursued if they like the look of that particular carrot. Doesn't have to be available out of the gate to be useful in the story.
More than a bloated character, I'd worry about a bogged-down CharGen process and an overall dilution of core-rules absorption. 
AM Chargen can be tough enough for the newbie - don't add to the overload.
This is the type of thing that is very Troupe-dependent. Some like that minutiae, some loathe it. If you know your group, you know the answer. But as mentioned above by others, Covenants has enough of a variety of offerings to make some of it "a good thing" to any play style.
Good point, and typical of most any of the supplements - each usually has a spectrum of goodies, and there is something attractive to almost any palate.
But I'd agree with (what appears to be) the consensus above - start with the minimal, add other stuff later. Ars has a vast collection of rules which can boggle the new player - no one rule is complicated, there are just a lot of them. Add stuff slowly, rather than all at once. If you like "the Title" of the book, if it calls to your imagination, then it's probably a good thing - if not, then don't bother (for now, at least).
True, but often if it's there the Player will use it, or want to. Even if not, they'll want to read it before chargen - and that alone can slow the game, if only by adding the rules needed for the SG and Players to know. The fewer choices/distractions to start the better; leave the advanced rules for the second mage character they build.
I think the key is to figure out what you are interested in - first "you" as the SG, but also "you" as the Troupe. (If the SG is not interested, the rest of the Troupe really isn't an issue.)
(Almost any Player should read the HoH book/chapter on their House - not critical, but good for colour and inspiration on both sides of the SG screen.)
Ars tends to be more accounting-intensive than your average game. It downplays money and detailed possessions, but library- and lab-texts, creating matrixes to aid in Spontaneous Spell design - anything to streamline it seems a good thing. And the SG will have more work than the Players - if one or more Players can be volunteered to help, jump on it.
Okay, here's some advanced AM game theory to think about, and this will help you avoid a major "spotlight" problem...
The most important character in any Saga is... the Covenant. The story centers around the Covenant more than anything else. Magi come, magi disappear, magi die (for IC or OOC reasons), but the Covenant lives on.
And the Covenant is largely defined by the stories the SG(s) want to tell. So...
Have your Players talk about what sort of theme/focus they want for their Covenant. If it's "independent activity", that's fine, but if two or more can lean in a general direction, then any one scenario can be about more than one Character's goals/desires. Sure, there are always tricks to dovetail multiple character into the same action, but with Ars, there are often so many Characters (at least 2/Player) that any economy of story-telling is a good thing.
If you let your Players build "anything", then either their choices will limit your stories (not always dealbreaker), or one of them will be the "fish out of water" if your story has a specific flavour. Especially if including Mysteries or a RoP book, make sure either that everyone is on the same page, or they don't care if it goes that way.
So... if one mage is interested in the Fae, and another in Demons, and another is a bunkered-in labrat - stories that develop all 3 Characters will be fewer (or just more convoluted) than if they all had something in common. Not that they have to march in lockstep, but they should at least not have contrary/conflicting horizons.
Also, I'd strongly suggest that Companions be conceived and created after the Covenant is formed, for the same reasons. Much better to have a Companion that fits with a perceived trope than one that demands a new plot element be inserted.
There are a number of (not so) obscure rules interpretations that can change the game or game world fairly significantly.
Consider and understand:o The "pink dot" problem.
o How Wards work.
o How Penetration works, and when a spell needs to penetrate in your Saga (and whether a ward needs to penetrate*)
o How the Text economy/trade system works. What is the average text, what are the paragons?
o How/if vis is traded in your Saga.
o How long 'til the next Tribunal, and/or the next Grand Tribunal
(* This effectively halves the strength of Wards against creatures w/ Magic Resistance, which may or may not be a good thing for you as a SG.)
(Any of these can be found on these boards w/ a quick Search)
So, all that said, in short, for the Players I'd recommend:
o HoH:____ - as appropriate to the PC's (and the SG should read True Lineages, and for any major NPC).
o Covenants - the parts that seem attractive/useful
o ___ Tribunal Book of choice (altho' not every mageling apprentices in the Tribunal they end up in!)
and possibly:
o Mysteries - "for later insertion"