Question 3 and 4 are impossible to answer, as no one has any data on this or has been released.

As for the increased crit rate on adloquium: It's all in your mind
Due to the nature of Adloquium, you look more forward to a crit on this specific spell. Have you ever counted the amount of non-crits? How often did you notice a crit physick, energy drain or miasma? The anticipation for a crit adlo pumps your body with some dopamine, which leaves a stronger impression on you whenever you do happen to crit on it. Go cast 1000 physicks and 1000 adloquiums (or more if possible), you'll notice the crit rate is roughly the same on both spells.

As for the ensured crit chance, you're going to need somewhere around 1350-1450 crit to make this happen. There's a formula floating around somewhere concerning this.

And concerning question number two: There was a mildly fired up discussion going on in another topic. I'll just forward you to that:
http://forum.square-enix.com/ffxiv/threads/204567-White-Mage-vs-Scholar-Why-is-White-Mage-lacking?p=2634448&viewfull=1#post2634448