~10 seconds faster depending if you get shot etc. if you don't take the Crane.

There's a pretty high chance Yasmin will be killed by not taking the Crane, She tends to run to the other end of the ship for some reason to kill those guys first instead of where the door/ladder is.

I think once you get to the bottom of the first ladder the deck unloads and it doesn't matter where she is or what she's doing. So take the Crane for safety unless you really want those ~10 seconds.

Yes, she is immune and runs off to get Eyebrows. The moment you cross the door into the Sol Vita.

Last night she died when I was halfway down the ladder, but I think once she says "I've got to get to him before anyone else" is when shes safe.

oh that is very possible! Sound queues are a thing.