To interpret some of this:
Maneuvers:
Pepperspray to the face is a weapons maneuver to place a tag like "Excruciating burning sensation!" Probably vs athletics to land, or you could argue endurance to resist.
Now with any maneuver you get that free compel on the tag. You're not paying for it, but they are either paying a fate point to get past it or GETTING one for accepting the compel. Still, you're going to then compel that tag, not to give them a penalty, but to invoke for effect and lose the spell or any other action.
Cost to you: one action.
Cost to your opponent: one action in exchange for a fate point, OR, one fate point.
Guarantee of success (meaning, opponent gets no action): highly variable. You have to land the thing, which is a contested roll, and then it can still be overcome by fate points.
Blocks
Simple enough, you make a spell to block spells. Bwahahah! This will block the TARGETING ROLL, normally, so if he fails to meet your block strength, the spell fails. If he exceeds it, then his spell will go off, albeit at a lower effect level (possibly, if he's trying for damage). However, you're probably optimized, and so is he, so it's more than likely an even match and is down to fate points and rolls to see who wins. However, honestly, if you're in a large party, he's probably statted higher than you (to present a challenge), so he might win this way.
Cost to you: normal spell costs, one action, possible fate points
Cost to him: normal spell costs, one action, possible fate points
My point is, there really isn't any one move (grapple) that can shut down a caster (grapple) that you aren't paying nearly the same amount to pull off (grapple). If you're just trying to protect your teammates or keep the bad guy from accomplishing something, there really is no guarantee of success, but these actions can be useful. If you're up for a longer battle, you can do these things by having 3 people manuever/block and only one attack - you've got a much better chance of taking the opponent out without them acting at all. But you're also probably giving them fate points in the process, leading to a concession (you don't get to kill them, but they fail at their objective) where they get even more fate points. The next time you see them, they're gonna just dump on you.
Which is why it's always good to use a social attack to inflict a consequence like "irrational rage" and keep them from conceding by bowing out of a fight
"I'm your huckleberry" IS a maneuver.