Having worked retail as a female and having a boss with a sense of humour, I was brought up with a twisted version of a Dutch saying:

The customer is king, as long as he behaves kingly.

I'd like to think that applies to SE too:

The user is an adult and peer, as long as he behaves like one.

So:

Is everything always up for discussion, or can discussion be axed?
Everything can be axed, if people aren't behaving like adults or peers.

Who's will comes first, users trying to hash things out on their own (especially when they are doing so successfully), or moderator fiat?
Users, but you can expect the CM to do their job when things get out of hand. The fact that they need to means we haven't been behaving like adults or peers.

Is my opinion just as important as some moderator's opinion, and the only thing that sets us apart is that someone trusted the moderator to act on theirs, or is the moderator's opinion more important than mine?
At the risk of making the authority fallacy here: the CM has way more experience, has seen other proposals of this site fail and knows why, moreover they are paid to deal with stuff like what they did, so I'd attribute a little more value to the CM at this point. Again, they step in when we aren't behaving like adults and peers, so at that point they become the teacher and adult in a space full of toddlers.

Is Stack Exchange a site for adults to respectfully and civilly work together as adults and peers to answer questions?
I certainly hope so, but remember the minimum age is 13, so adult might be a little overdone. I am glad there's moderation to take care of people behaving like they're not 13 yet though.

Having worked retail as a female and having a boss with a sense of humour, I was brought up with a twisted version of a Dutch saying:

The customer is king, as long as he behaves kingly.

I'd like to think that applies to SE too:

The user is an adult and peer, as long as he behaves like one.

So:

Is everything always up for discussion, or can discussion be axed?
Everything can be axed, if people aren't behaving like adults or peers.

Whose will comes first, users trying to hash things out on their own (especially when they are doing so successfully), or moderator fiat?
Users, but you can expect the CM to do their job when things get out of hand. The fact that they need to means we haven't been behaving like adults or peers.

Is my opinion just as important as some moderator's opinion, and the only thing that sets us apart is that someone trusted the moderator to act on theirs, or is the moderator's opinion more important than mine?
At the risk of making the authority fallacy here: the CM has way more experience, has seen other proposals of this site fail and knows why, moreover they are paid to deal with stuff like what they did, so I'd attribute a little more value to the CM at this point. Again, they step in when we aren't behaving like adults and peers, so at that point they become the teacher and adult in a space full of toddlers.

Is Stack Exchange a site for adults to respectfully and civilly work together as adults and peers to answer questions?
I certainly hope so, but remember the minimum age is 13, so adult might be a little overdone. I am glad there's moderation to take care of people behaving like they're not 13 yet though.