[Kreugen]

I'm not as far along as most, but I find it really cool when you get bits and pieces of understanding from various characters. Cotillion is a walking spoiler. So just to test my own knowledge, I ran through your list.

The humans that do use Elder (like the Cedas) are actually using Holds instead of a warren. The problem is have such poor control over it that they are likely to kill their own troops as the enemy. They pretty much conjure the power straight from a Hold, then give it a direction. Midnight Tides has tons of it. Basically, in other parts of the world they don't even know what a warren is, they still use Holds, which are Elder by default. Warrens = easier, more control, more limitations. How does one learn how to harness a warren? No fucking clue. God worship is one path, though, so I guess the reason human's don't get Elder warrens is they have forgotten the Elder Gods. The only other mortals using Elder get horribly deformed every time they use it. Pretty sweet.

T'lann Imass aren't the best individual fighters by any means. You already stated why they are feared - they can move unseen, they never die, and there's a lot of them. I'd say that's a rather large advantage over Joe Footsoldier. To give you an idea, A Forkul Assail kills tens of thousands of Imass by itself. The vast majority of Imass are off fighting an unending stalemate on another continent that hasn't even been dealt with in the story (Assail) Only one clan fought for Malazan.

The deal with their warren is kind of confusing. They are part of the deck and aligned to their own hold (Tellan), but they abandoned it to use the warren of fire (the whole ritual to become undead thing) This means their throne was conveniently empty for Kelanved to come along and scoop up. Tellan's control over them is weak now, though. And that's the limit to what I understand there, and I'm up to Bonehunters.

Gods - there's different kinds, but all are beings with worshipers. Sometimes, worshiping a primal force (like a storm or something) actually causes it to become a sentient being. If the worship dies off, the God returns to being a mindless primal force. (or part of Mael's underwater Zoo?) They aren't necessarily any more powerful than a rank and file ascendant.

Deck of the Dragons - wasn't this already explained by now? Its how Order (Lady Dark) keeps everyone in check. Its pretty much a giant metaphor made physical. Aligning to the deck both grants and limits power. It binds ascendants to certain rules. Its either really cool or kinda cheesy, I haven't decided yet.

Ascendants - aligned are beings chosen to fulfill a certain role defined by the deck. Unaligned are just anyone that has been gifted with power in some way. Stormy and co, for example, absorbed some power from their trip through the warren of power.

The apostrophe thing - most of the current names are bastardizations of the ancient names of various races.

Magic is often Tolkeineque, more of a force of will than fireballs and lasers. But there's plenty of that, too, especially in Midnight Tides. (Chaos magic = holy shitballs) When he talks about unveiling a warren, its basically like opening up the floodgates and letting raw power pour out. There's no shaping of a spell involved. You just point, aim, and let the shit flow out. So yeah, the scene where Ben blasts the Crippled God probably looked something like the Care Bears shooting rainbows from their chest.