"3) How do you describe a room to players so they can map themselves and begin to exercise agency within a dungeon?"
Our final question from Ryan asks about describing rooms to players.
In my personal experience, having run dozens of campaigns over the last twenty-four years is that I have never ever read any piece of boxed text that wasn't ignored after the first sentence. This is my experience with hundreds of people. David Noonan and Jesse Dexter talk about that here.
Now because this is the internet, there are some contentious bastards out there who will say that boxed text is what they love. They sit back, close their eyes and it really allows them to imagine the room.
That dude is an a**hole.
Dungeons and Dragons is a social activity that involves the exploration of a fantastical space. Reading boxed text is neither social, nor exploratory, nor is listening to a lecture fantastical, even if it is about demons riding naked women to a lazer gun fight in space.
You may like boxed text. You may think it sets the 'tone' of the module or has descriptions that you would otherwise not think of. But without fail, if it is longer than two sentences, the vast majority of players will tune out. The only person who will actually be exposed to the atmosphere and tone is you, because no one else will ever hear it. The philosophical ideal of "This will provide a cool description" will be eliminated instantly when the players tune you out, because you are a dude who's job is not reading things dramatically, reading from a text you have never read before.
I mean, unless you practiced reading aloud boxed text alone, in preparation.
When I prepare a room, I use set design to key the map so I have clearly in front of me all the immediately visible information. Then when presenting that, I focus my efforts on describing those things dramatically.
This has all the advantages of boxed text without any of the disadvantages. The items the player's can see are set apart from the items they cannot. It insures that no critical information is missed in the presentation. It presents things in a manner that is quick and easy to parse. When you present the items, you will be conversing with the players instead of reading to them.
The actual procedure involves finding out where everyone is standing and who has light sources and such. I interact with the players to determine the fictional positioning. This is negotiated*.
Then I glance down at my sheet and describe the size of the room ("This small room contains. . .") and immediately visible objects. This usually takes only one sentence, keeping everyone engaged. As they explore ("I look at the. . .") I expand on each of the descriptions.
If there isn't anything crazy like a battle or someone pulling a lever happening, I will tell the mapper in short order the actual size of the room. Why do I do that? It is part of the assumption of the slow movement rates that they are making relatively accurate maps.
On a bad day, it consists of me listing quickly what's in a room. On a good day, it allows me to spend my time focused on presentation and maintaining interest in the conversational flow.
*Negotiated fictional positioning means that position isn't tracked closely and it isn't always clear where everyone is, so we negotiate as a group to determine the reality of where everyone is, from the stance of what is real, likely, or interesting, rather than everyone approaching it via, "what is best for me".