Two Questions/Guesses

1) Prof. Quirrell pointed out that Harry was especially vulnerable to the "Finite Incantatem" spell (to removed his transfigured armor). How does the canon mechanics of this spell work from a tactical standpoint? Is it area of effect or targeted on a per spell basis? Can a weak 1st year dispel a casting done by Headmaster Dumbledor or does caster strength play a role in its effectivity? Depending on the answers, Harry's vulnerability could be mitigated by pure strength or recursive spell depth or minor covering spells to absorb the dispelling castings. 'Just saying. :)

2) In terms of world building, I wonder if Harry is considering that he's got good evidence of living in a "matrix style" simulation with the reality glitches that is the existence of magic. It seems to me like just so many reality "cheat codes", hence Harry's inability to derive underlying principles in the operation and physics of magic. Indeed, the whole hero/quest/prophecy shtick would also count heavily towards a simulation argument.