What about PC deaths? Are there any general guidelines for handling this? This seems like an RPG that is MUCH more prone to PC death. How do you avoid players feeling left out when they die?
In a campaign I am sure you can just introduce a new character, but what about one-shots? Do people feel left out if they are “eliminated” early?
In my case, I think it's very easy about one-shots... All the players have to know that they are playing "Alien" (not the "A-Team, the RPG"), so it is going to be common that a player could be killed by a xenomorph, a NPC or even another player. In my case, all my players have assumed this and though it's never always easy that your character could be killed, they have no problem to choose another one from the NPCs available and keep playing the game.
It's important to note that players are playing for Story Points, that's one of the goals of the one-shot scenarios, so it's not so important that your character survives but to roleplay him/her in a right manner, no matter if he/she dies accomplishing his/her agenda. I would remark this to all the novice players. And in my experience, all (ALL) the players have played trying to accomplish with his/her agenda no matter its difficulty (and there are difficult ones in "Chariots of the Gods" and "Hope's Last Day").
Of course, the other important point is the fun... What would it be an "Alien" movie without extreme risks and danger? I have seen this too in my plays. When a character dies, his/her player assumes this saying, in general: "It's Alien".
So I would say that don't worry with that in one-shots.