Oh well , if there is going to be another thread .... 
One thing occurs to me ,
is that of using CrMe to put memories in your head.
Well. The player is me. And the character is a pet project I am medling with out of interest and out of the hope that some of my players might realise their plans of daring some beta-storyguiding, and thus giving me the opportunity to play a magus myself. I do not want to bypass the flaw - it is what gives him flavor and the reason that I chose the flaw over so many others granting other interesting opportunities (for play). That is why I won't have him reproduce sight, but to manage without it. To the character this might be because of essential nature or it might be that the cause of him loosing his sight makes him humble and not wanting to work against something he sees as the reason of some higher will.
I have deliberately, even if he is a Intellego and Imagonem specialist, avoided the InIm spells that give you impression or sight from afar (or nearby)
You might consider having him start with either a spell, or a magic item that reads out loud to him... (allowing him to hear text...)
He's trying to do that in another thread. The problem is that magic can't read.
You need something with a Mind to interpret the writing.
You could take Ghostly Warder (page 43) and have it read to you.
Which has the "downside" that the ghost might prefer to read something else than what you intended...
"Banishing Ghosts For Dummies? Who would ever want to read such a dull book? Here, dearie this is better: Mary goes to the fair. You always loved when I read it to you when you were little."
I was thinking more of the Ghost of your old Latin Tutor ,
not the governess you may have had as a young child. 
This does present it's own problems in choice of reading material by the ghost.
(They are meant to be quirky after all)
This is a great idea but it begs the question, just how did this Tutor die?
I mean if you killed your best Tutor to get the ghost, even if they adored you, this might change their disposition (if they know they are dead).
I think the ST would preclude you murdering someone to get a Ghostly Warder ,
this would be Plagued by Supernatural Entity instead.
You might have accidentally caused their death , but not on purpose.
Plagued by Latin Tutor From Hell. shudders
I prefer the plagued by greedy ghost dragon in a sword one of my players got in a game....
Lessons delivered by ghosts? I thought they always came in threes - past, present and future, and only at christmas. 
Ebenezer! Your Tudor is here.. ahmm... tutor!
Hello ! This is my first message. 
I've just made my first magi hero.
He is a Mentem specialized hero. One day, he will become the strongest of the whole world in Ment/Imag/Vim.
I think he would be able to make (some day...) a IntMen spell, to detect souls around him so he will see all people, invisible or in animal form that will not matter... This should be efficient, isn't it ?
But i have a question :
I've got the second sight virtue.
I know that it allows u to detect invisible creatures (ghosts, devils...) and faeries powers.
But is that virtue allow u to see invisible magi heros ?
I feel that it would be quite strange, if i were able to see the best invisible creatures, and not being able to see a little magi with a simple 15 PerIm(Co) power (if not moving).
But perhaps that virtue would become to strong if it would allow that... 
Page 67 gives the rules for seeing invisble magi. The Ease Factor is 6 + the magnitude of the spell concealing the magus.
That is really interesting.
Was that in ARS 5th, 4th or 3rd edition ? (my current one is the 3rd, cause this is the only one in french... 
But i have the 4th too, i got it freely in english)
Does it allow me to see all spells hidden at sight ? (which can be traps, concealment spells or regio spells...) For instance i could see colors, just to deduce their type...
What is the ease factor for :
- devils ? always 9 ?
- and for ghosts ?
- and faeries ?
Is it constant or does it raise when the power of the creature raises ? (as it should)
Then that means i should search for new spells IntIma(Ment) to increase my Per skill, so that no one will escape from my sight... (the mentem requisite would be to reach a perfect attentive state of mind)
By ur advice, how much bonus can i expect to obtain with this kind of spell ? and for which magnitude ?
Is it possible to create Vim spells, to increase my second sight virtue ? (for instance to raise its efficiency, or to make it more sensible to some kind of concealements, or to extend its capabilities to other invisible things like magi itself)
This is very interesting, because i'd like to make this powers last until down without concentration. So i'll be in a "radar state" as soon as i'll get out of my laboratory.
Unless specified, assume we're talking about the 5th edition. Trust me, you do want to get that one. 
No, it allows you to see things which are invisible (e.g. ghosts, invisible magi, etc) and see through illusions. It also allows you to see through regio boundaries. It doesn't allow you to see magic in general (check Magic Sensitivity instead).
SG call, I'd say.
It would have to beat the power the creature is using to conceal itself. If it is merely "naturally" invisible, I'd keep it a constant.
If you want to raise your Per, you need Creo Corpus (or was it Mentem? Can't remember off-hand.)
Intellego wouldn't help: you need Creo requisite. At that point, you might as well make two separate spells - or more, since you'll need many distinct detection spells.
Depends on what the spell does.
In 5th edition, you'd use Intellego spells with sensory targets to grant yourself new senses. It has nothing to do with your virtue.
Watch out for Warping (or Twilight) due to constantly being under the effect of a spell...
I never thought it would come to this : Trust him! Trust Fruny! 
Even if I always loved Ars I really have a hard time understanding how I ever managed without 5th edition.. It is a completely new game, yet all the same, just a seven-league step better!
I don't understand. What does that mean "SG call" ? (english is not my native language... 
)
Great !
Well, i think that if u want to raise ur eyes or ur ears capabilities, u need Creo Corpus. That will give u a way to see and hear things from farther then simple human beings can do.
But i feel i need 2 things :
1- i need to increase my awakening, my concentration, i want to be more attentive. So i need Creo Mentem... 
What i need, is to see a invis entity if it comes near me. It will not be a problem of hearing or seing something from very far...I guess it's just a mental problem : am i always seeking invisible entities ? am i always trying to find them ?
2- And even if i know an invis entity is there and i'm seeking it, I guess that 2nd sight, the skill itself, requires a good mental state. Not the best eyes. Because i feel that eyes have nothing to do with this kind of capabilities... When something comes in front of u, if ur eyes can see it u don't need any die test. U just see it... But of course i can't be sure of that.
Well, if i want to be more attentive, i can have a bonus for ALL i would like to see with a CreoMent spell . But a bonus of how much for which magnitude ??
And if i create a 2nd spell, an CreoMent one to increase my skill for a specific target (if it is possible i don't know), the choice will be easy: this skill has an ease factor of 9 for all except magicians... And I have 1 or 2 in Per + 4 in 2nd sight, so 6 + a die to see all i can (+ the bonus of the first spell 
).
So without any spell i will fail only once per 10 tests (with a "2") except for magiciens... And with the first spell i will never fail any test !
So i should make just 1 specific spell for magicians. The others are quite easy to see !
Well... i guess i'll be out of my covenant 2 or 3 weeks maximum per season. Do u think i will risk twilight if i'm under the effect of this spell(s) 50% - during the day - of this 3 weeks per season ?
SG is Ars Magish - it means Storyguide.
Concerning you other questions I'm afraid I'm a bit rusty - even if 3rd and 4th are on my shelves I have difficulties setting aside my "5th ed. perspective".
Creo Mentem can enhance your Perception, Intelligence, Communication and Presence - but it is rather high-level spells and they cannot go beyond human perfection (+5 in any given characteristic). Else you would have to use Muto Corpus - and maybe gain som animal sense by using Animal.
Creo Corpus can do the same for Strength, Quickness, Stamina and Dexterity.
So i can expect a +3 bonus on my perception. This is great !
But about which spell level ? (i guess my AS will think like me that the lvl of the 5th edition is valid for the 3rd or the 4th...)