Well, duh. We wouldn't want to take away story fodder! But I'd still say it's easier if resources can be shared towards the goal.
The word "research" has a particular meaning in this context. It means seeking after breakthroughs.
It's usually a much more efficient use of your time to try to invent magic within existing Hermetic theory than to try to develop a completely new discipline. Breakthroughs are usually developed by extremely dedicated Bonisagus lab rats who aren't after power so much as prestige, and in particular a chance to revolutionize the Order.
I thought it was ArM4 that had the mechanic that made you more likely to get killed with armor in combat, not ArM3. Serf's parma, it was a long time ago that I played ArM3. And I'm remembering Frank Trollman's review that says the fix for this is ignoring the encumbrance penalty for combat is how it was fixed...
By that I mean the science of magic is a modern day mindset that expects when you perform the same operation two different times, you expect to produce the same result both times.
The art of magic is a mindset where it is exactly opposite - if Leonardo painted the Mona Lisa TWICE, the second painting would be similar, but different, and he would have expected this outcome. Same thing for magi, it's HARD to get consistent results, rolling a die simulates that.
M:TA looks at magic with an essentially modern day scientific mindset, even if that outlook is not necessarily supported by the actual rules.
Coming back to heart of the matter - most of your questions on the forum deal with essentially a simulationist perspective, but ArM5 is a Storytelling perspective, more concerned with living the stories than the mechanics that produce them.
Technically, Ars Magica is about half way between an Art and a Science.
After all, that's the whole point of stabilizing your experiment. You're identifying all the external factors that can adversely or positively affect the work you're attempting.
And when working in the lab on normal works (such as crafting a spell, or an item) you have a lab total which means if you try the same thing time and time again it IS consistent, so that's a science. The reason magic is an art is because magi can't account for ALL the external factors. Some of it is "Does God feel like it today?", others are "Am I wearing my magic wizard hat at the right angle?", yet others are "Is that actually a knight, or a demon pretending to be one, or a fae pretending to be one, or a real knight with a holy relic?"
The art of magic is judging if you can compensate for the external factors. The science is the knowledge you have on how it works.
with respect i think i disagree on art and science.
i think mage is more like art because (reasonable rules and limits aside) youre mostly concerned with matters of belief. if you think you can do sth and can explain it paradigmatically(and have the dots) you can do it. this is not always applicable thus mages did not makeevery single spell on the fly of course some did need lots of time. but for the most part this is how it is.
in arsmagica however while your belief(tradition) does seem to play a roll for the most part youre like a scientist. for instance formulaic magic is like a scientific procedure. it has very litte flexibility. spontaneous magic is weaker. you need to experiment to discover the rules of magicto alow you to do a new thing(e.g a duration)
now athough the system does look a bit .. like the opposite extreme of mage in some areas to me, i do like it. to be fair one of the things i did not like in ascension was that,for all intents and purposes youre not a mage,youre a reality warper
No, Warping and Twilight are a part of Hermetic magic, each source of warping is treated as all being the same, and it all pushes a magus towards Twilight.
Botch dice are not added based on aura strength of the power used is aligned with the realm. Merinita, being aligned with two realms don't have to worry about both dice additions in magic and faerie auras.
A holy magus, acting in accordance with the will of God would not have that number of botch dice...
Twilight can easily be avoided, as long as you are a bit careful. You don't even need any of the Virtues you were talking about; you can botch, you just need to avoid double or more serious botches. As long as you avoid casting in foreign Auras (Magic ones are fine, and with the appropriate Virtues those of other Realms can also be), and avoid using (too much) vis in your castings or for your studies you can keep avoiding Final Twilight forever (and remember that by the time you are old, you are likely to have a fairly strong gold cord, probably at least +3).
Decrepitude -- at least for Hermetic magi using Longevity Rituals -- is a different story. It will kick in eventually. But with good living conditions, a personal physician, a fair Bronze cord ... you can easily reach 300 years of age, even by brewing your own potions and without any special Virtue, by devoting perhaps 1/3 of your time to the study of Creo, Corpus, and Magic Theory (of course, having a specialist, probably with a Focus on Aging and/or Affinities etc. is a more efficient way of doing it). By the time you are that old, if you really want to keep on living, you've probably come up with some other method; most involve turning into a being of Might (which has the advantage of making you immune to warping/twilight) but you could also take Faerie path of Becoming (from HoH:MC) stopping "halfway" like you've mentioned (technically possible according to the Rules As Written, even though the author did specify on these forums it was not his intention), or take the Immortality of the Forest route (from GotF), or learn the secret of the Sahir's elixir (from tC&tC), or have a someone with the Faerie Bonding minor Virtue bond a Faerie to you (from RoP:F), or learn the secrets of the Zoroastrian Holy Magi (from tC&tC), or join House Criamon and study a path like the Path of the Body (from HoH:MC) or go the Infernal way and have someone Bind a spirit to you (from RoP:I) or use Maleficia to dump your Decrepitude onto someone else (again, from RoP:I) etc.etc.
The math involving auras and botch dice when casting spells is relatively easy and can be found on p.183 of the core book. Only foreign Auras add botch dice to the spellcasting rolls of a magus; they add 1 botch die per point of Aura, so casting in a foreign Aura with a strength of 10 (the strongest possible) gives a magus 10 extra botch dice.
Magic Auras are never foreign to a magus, so they never add botch dice to the casting rolls of a magus (but neither do they remove botch dice). Typically Divine, Infernal and Faerie Auras (even if the latter give a magus a bonus) are foreign Auras for a magus, but some Virtues can change that. For example, if a magus has (like all members of House Merinita) Faerie Magic, then Faerie Auras are not foreign to him. A magus with Chthonic Magic (from RoP:I) does not treat Infernal Auras as foreign, and a magus with Holy Magic (from RoP:D) does not treat Divine Auras as foreign.
Each point of an aura adds another botch die, and doesn't add botch dice based on the penalty due to realm interaction. The penalties and botch dice only apply if it is a foreign aura.
There's a pretty comprehensive breakdown of how it all breaks down in the page ezzelino referenced.
As an aside I've always wanted to make a character who tries to acquire all three of those virtues. Maybe a Merinita ex-diabolist trying to purify and redeem his magic or a member of a holy yet darkly sinister order of Ex-misc monster slayers.
"I'm learning this so I can hunt the witches in their lairs."
Now, witch-hunting is itself a very morally-dangerous area - but a knowledgeable Holy Magus with Sense Holiness & Unholiness and solid skills in the appropriate Lores can probably tell when someone is actively working to claim souls for Hell. ...right?