OOC:
While Qralloq is far more educated on this system (and his rule on how everything works is law), I've been reading through a lot of the manual, so I'm getting familiar with this pretty quickly.
OOC:
Generally, a creature's "level" is the same as their difficulty. This creature is level 3, so its difficulty is 3, and the target number you have to roll for is always (difficulty*3), or 9. The initiative to beat is difficulty 3, the difficulty to hit the creature is 3, the difficulty to defend against when it hits you is 3, the difficulty to sneak by it is 3. I kind of like the simplicity, honestly. Tougher monsters makes everything tougher.
Everything in Numenara has a "level". Creatures, objects, NPCs, cyphers, all of it. So if we find a cypher that's level 4 and someone wants to identify it, that's a difficulty 4 task, target number 12.
Easing lowers the difficulty by 1 (target number down by 3), hindrances take the difficulty up by 1 (target number up by 3).
OOC:
Yes, Effort is one of the main ways to lower a task's difficulty by 1 step. You can also use Effort to increase the damage of an attack by +3, though I don't know if you can do both at the same time, that's DM's call (though, right now your character's total Effort is 1, so you can only use a single instance of effort at a time).
Effort costs 3 points from the associated pool for the first level, and 2 points for each Effort level after that. Later in the game, if I want to use 3 levels of Effort on a task, it would cost 7 points (3 for first level, 2 each for next to levels).
Edge reduces the cost of effort. If Emmett wants to use 1 level of Effort to ease a melee attack, it would currently cost him 2 Might points instead of 3, because his Might Edge is 1. I don't know what pool Lyle's Edge applies to, because Jacks can choose 1 Edge point in any pool at character creation. Nanos have 1 Intellect Edge, Glaives have 1 Might Edge and 1 Speed Edge.
As your character advances in tier, if you eventually get 3 Edge in one pool, then you can use a level of Effort for free from that pool. I believe after that, your next Effort still costs 3 points, though.
I hope I didn't make that all super confusing, and if Qralloq has a different view on it then his view on it is the correct one. Feel free to ask me any questions about the system, I feel like I've got a pretty good handle on it thus far.