Skyscrapers & ... Groundscrapers? (RP)

You can roll Techie (presumably +Insight) to see how well it goes (though the results may only materialise later, after you have left, unless you take the time to Rest here).
If you hurry and smear some samples on the bodies and join the others, treat it as a Serious Disadvantage -2 [rules].
If you leave the others to do their thing with the fight, but don't take the time to do meticulous science (which could advance the Cloud of Woe as per Resting), treat is as a Disadvantage -1.
If you want to roll without a Disadvantage, then it will take long enough that every else can Rest or Scrounge (after dealing with the fight if they want to (the fight can be far enough away that you can, possibly, stay out of it)).

Is there any downside here for Fiona turning to join the fight immediately AND THEN spending the long period of time trying to revive these people? The fight will likely last less than a minute, after all... And those goblins are probably transformed humans too, so if she's gonna save lives, killing that bug more quickly, before it eats more goblins, could do so as well.

Roll for Damage. Which is 1d6 unless your weapon says otherwise.
• On a 1-2 you do indeed make it angry and it charges you, and bites (at) you. (You can roll another attack and avoid the bite on a 10+, you both take damage on a 7-9.)
• On a 3-4 you make it very angry, it charges you, but is slowed by the wound and you get a chance to take another pop at it before it gets to you, maybe you can kill it in time.
• On a 5-6 you make it scared and it flees, it may die off-screen, or you can chase it and finish it.
• If one attack scores more than a 6 (7 or more (remember you can add Strain to any roll)) you take it out and impress the goblins.

You can probably narrate the outcomes based on the damage roll. Herman can join in.

I know early PbtAs made a big deal to the GM about 'Make your move but don't speaks its name'. I always treated this as '... don't just speak its name' rather than 'never'. Sometimes, in addition to seeing the outcome in the fiction, it helps for the players to understand which GM Move is being made, (or to be reminded that Moves like 'Take away their stuff' are in the rules).

In this case, the consequence for the 5 is that you learn ('reveal an unwelcome truth', maybe) that the centipedes have more armor than expected (even I did not know it was that tough:). (And a little more that you may discover later.)