1. This is a bug and I already know the reason 😅
2. I assume you play on the expert difficulty. Regardless, this definitely needs some balance, I'll work on that.
3. Close the doors, use alarm or use the ship scanner to see where it is at the moment. I'll make a proper indication of its presense and movement. Also it cannot kill you if it doesn't see you, so you can just hide or move to another room. You'll need to wait until it becomes less aggressive or leaves the ship.
4. Heart rate means something "scary" happens, in your case it's definitely aggression of Breathless. I guess this needs more visual feedback to indicate that something is going on.
Huge thanks for playing and reporting these issues! I'll try to publish the next update with all the fixes as soon as possible.