For yoshi death go in kol route and deny him the shower together. Then an option will come up when you are in the gallery and Nasir will ask if you really want to fuck kol. Choose 'No' here and Kol and Nasir will mercilessly grab you and throw you out of the airlock
You'll only be presented with this option in Chapter 8 if you didn't kiss Kol when you had the chance in Chapter 7, and then you didn't let him shower with you.
