@Girlie1Bomba good questions! I'm on my phone so forgive formatting and autocorrect issues haha.
The living ships are kind of rare and extremely expensive and don't have a very positive reputation: they're probably known to be more trouble than they're worth, and they're not being made anymore (though there are rumors they've been reproducing on their own). The pcs likely have heard of them but wouldn't have seen one before.
Battleship version: I'd say a few battle versions were made like this ship, and most battleships have some level of organic structure or sentience, but they're mostly machine. The Helium Frightful is mostly organic, which is rare and not desirable to most.
Helium makes actual noise most often, but can make sounds on a level similar to Witnessed and Whisper - so yes to telepathy, but not exclusively.
I didn't even consider the interior flexing with the movements! Maybe it bends, but slowly and only at wide angles. Nothing that would impede your path, but maybe rooms aren't always exactly the same size, depending on where they are.
You've got mechanical noises and organic noises: gears and humming and whirring and heartbeat and breathing and whining and growling. Good luck sleeping! :D
Lucky has probably been on a vessel that was alive at least in some part, and it's possible it could have been alive to the same degree.