So, our formation for the smaller southern tunnel would be:
Front: Beldarion and Og'rialt
Back: Sulibor
(?): Rudy, who wanted to go alone (did Og'rialt warn him about the fire trap?)

Active spells: Detect secret (Sulibor)
Active traps: Fire trap at the entrance (Set by Og'rialt)

"Hmmphh." Roy steps into the western tunnel with whoever is in there (as that's where he's closest to). He says to whoever is in the tunnel with him, "Need to slow them down, maybe some stuck food will keep them busy as we go our way". I give Siegfried a grin, and cast web in the center of the room.

Rudely ignored though we were by this human ranger, I did indeed point out the trigger mechanism for him to avoid, as he does not appear to be many clawed. I suggest we let him pass us by, and wait momentarily for the effects of the detect secrets spell to become clear before rushing deeper into the unknown. Mayhap we'll encounter him again later; perhaps his fresh corpse will at some point warn us of a trap!

As I finish setting the trap and prepare to leave it to guard our back, I look back into the circular chamber. Of those nearest the southern tunnels, I see a half orc waiting around, a party of three entering the main tunnel and calling out to two more to join them, a single mage entering the main tunnel while casting a summon monster spell, and a thief listening at that same tunnel.
Meanwhile, the drow, a halfling, a human, two elves and the two called upon by the party of three, have yet to take any action.

I call out to the Elven thief listening at the southern tunnel, taking note of his decision to grab a torch for himself, "Hey, friend, there's strength in numbers, and a small tunnel is easier to scout for traps than a large one. Care to join us?"

Turning toward the remaining group, including the two who have already been called upon by the other party, I call out "I extend the same offer to you. If your purpose here is to get out alive, then let us work together, and be smart about it!"

I leave it carefully nebulous if I do or don't include the drow in my offer. My own sensibilities have not yet come to a conclusion. As a cast-out from dwarven society (by choice!), I tell myself over and over that I do not want to judge those who live differently, and I see that the drow is just as befuddled as I was to find himself here. He is not many-clawed, and will want to escape as much as I do. And yet everything in my upbringing screams out that the way drows live in darkness, underground, is in every aspect a perversion of the One True Way which has been taught to dwarves since the Beginning of Time. And if I can overcome my own sensibilities, could I convince my fellow party members to do so as well...?

Fognino, the Goblin Shaman, is still biding his time, looking with attention to each forming group in search of the most promising one to follow.

Moving his staff, he starts to chant a Goblin spirit mantra to attract the attention of his greenskin similars with the aura of authority each tribal shaman always has in tribes. It is time for Goblins to plan ahead.

Babaargh the Dwarven Cleric
Greetings to you all! I would be more than willing to join up for collaborative exploration. I hope we can convince the Son of Fulvus to join our party as well, I feel the skills of a thief would be well placed in these halls.
As for myself, I summon a Holy Guardian
Let me figure out whether I can extend my Globe of Protection to more companions than myself before I cast that as well.

Me Pater Alf, Half-Orc Warrior, joins Cardan and Balbok. Also brings tiny cute pet potato Olmse. Me very stupid, but strong. What we do next?

Fish the half-orc shoves aside the other adventurers to get a better view of what's ahead in the western tunnel. He sees only darkness. He grips the handle of his great axe and already imagining how many creatures he will get to kill this day.

Calad the Elf Mage eyes the room anxiously, first because of all the people, before noticing the scraping coming from the grate and adding one more reason for his unease.
The chests eventually attract his attention, but he decides to let the people already working on them keep doing so and not approach. The chains appearing after a Detect Secrets spell was cast are another point of interest, and it follows that, being hidden, they would be in some way beneficial, but what will it be required to make use of them? It seems more of a risk taken upon oneself to pull one, perhaps if not all are pulled at the same time, or perhaps if they are.
Watching Elven Necromancer blending himself into a column, he smiles bitterly, wishing he could do so as well, but alas, it is not the case. As such, he turns his eyes towards the East Tunnel, which he found himself nearest to, and sees what appear to be the fewest adventurers heading down it at this point. In truth, only Garethianopolisian and Lady Beatrice Eilonwy Giulietta Giselle went ahead with determination, Balbok starting to follow behind them but then apparently deciding to wait for other Half Orcs, what he, Cardan and Pater Alf will eventually decide to do being unclear at the moment.
Still, a group of Half Orcs seems like one a scrawny Mage could do well to stick around, so he sort of hovers next to them at the entrance of the East Tunnel, trying to catch bits of conversation and, if it would seem to be a good idea, work up the courage to try to join them if they're heading in the same direction. But since interacting with unfamiliar people may well be harder than facing a foe, he may well simply follow them without a word.

-----
Calad - Elf Mage - tentatively heading East

Kip (Halfling Brigand)

Kip will join the party heading into the small southern tunnel.

He will volunteer to take the first rank (he's good at spotting ambushes) if Og'rialt or Beldarion wish to swap out, otherwise he will happily fill a rank further back instead.

Roark is still yanking away at another chain, while Darrim stares upward. Catching sight of Cicatrix testing the chain, he waves enthusiastically. If she starts climbing, he'll follow, giving Darrim a boost if he wants it.

Roark, Elven Druid

Noticing the increased pulling on the chains, Calad wonders whether they may close the tunnels, protecting those moving forward from whatever threatens to crawl up into the central chamber (if at the same time preventing them from fleeing back from threats found ahead) but dooming those still in the chamber, including those pulling the chains. With that thought, he moves a few steps farther into the East Tunnel, regardless of the eventual decision of the group of Half Orcs. There are two others farther ahead, at least.

-----
Calad - Elf Mage - tentatively heading East

Agreed

Stephareth, Human Necmomancer

*The first words of Daddy Burrson after waking up were "There is no way I'd drink that elfish ale again!". After spending at least half hour in (unsuccessfull) attempts to remember what happened yesterday and how he s ended down here, he slowly checked the chamber, he s found himself in. Looks like there were other people, but they are... gone? Still blaming the damn ale, he slowly walked into east tunnel*

(in case there are logical holes between my turn and other people's actions - lets say that said ale had side effects and Burrson is unable to see other people for this turn)

Seeing as how most of y'all hate me, I decline the invitation to join your party. I wish you health.

Rizzleskiff heads into the smaller Northern tunnel, lingering so as to be the last to enter, keeping a good 50 feet at least behind any others who are entering the same tunnel.