Heh, #3 was going to be "What's up with the weapons-grade entropy curse?"
It seems like the aspect it places is definitely going to have the one shift it needs to be sticky. If that's the case, and the first free tag compels a 26-strength attack, what happens when the sticky aspect is compelled using fate points? Can you spam 26-point attacks on the target for the remainder of the scene, at the cost of one fate point per attack? Seems broken. Also, is surviving the curse as easy as having a fate point to buy off this compel?
The best answer I can think of is that the spell really just gets treated as an attack, just like Victor's Heart Exploding spell, and that describing it in terms of an aspect doesn't really mean it should be treated using the usual rules for aspects.
Here's #6:
What's up with stacking two maneuvers to get multiple tags, as described on p. 265? Specifically, if I'm casting a 2x +3 maneuver spell on a target with good conviction, for a total of 6 complexity, does that target defend against a 6-point maneuver, or does he defend twice against the two separate 3-point maneuvers? If it's the second (two defenses), why wouldn't I just cast the two 3-complexity spells separately? I'd spend a little more time casting (given the minimum ~1 minute per spell), but wouldn't need preparation.
As for #5:
So lets pretend Harry is bringing a nonmagical friend to a dangerous meeting, and wants to do a quick (no preparation) defensive ritual before heading out the door. If we assume the base duration is 15 minutes, he could give the friend a minor edge (+1 block) for an hour, or a bigger edge (+2 block) for 30 minutes. A serious thaumaturgist could do better (probably +5 lore +1 specialization +1 focus item), applying a +2 block to the friend for a full day, or +4 for a few hours. If the duration is long enough, you've got time to repeat casts and get *all* your friends.
This doesn't seem radically broken, but I think it's pretty significant how bumping the base duration up or down a few steps makes this kind of spellcasting dramatically better. It probably still doesn't compete with evocation for maximum shielding power, but depending on the base duration, you can come close without sacrificing actions and mental stress in combat.
And for #1:
There are a loooooot of applications for beneficial aspects, "good luck" being the most obvious. Normally, beneficial maneuvers are done during combat, when it's clear who's contesting the maneuver--e.g. distracting someone who's trying to gain "Deep in concentration". But thaumaturgy usually takes place long before it's clear who might oppose the beneficial aspect.
Example spell:
Burglar's Blessing
You apply the following aspects to yourself: "Steady Fingered" & "Nimble Climber". Each has two free tags. The effect lasts for an hour.
Complexity: 6? (2 aspects x 2 uses + 2 duration shifts)
or maybe 10? (8 total points of tagging boost + 2 duration shifts)
...but if it's 10, does that mean it's easier to curse someone with 1 or 0 conviction than it is to bless yourself?