1: So was Alien in terms of actor numbers, and even the actual age of the primary cast - but these are meant to be young adults (mid 20's) stuck on a planet that won't let them leave, basically change in language since the 70's.
It's worth noting that doing a bit of a dive in the alien lore, the main character is about the same age that Ripley was when Ripley signed onto the Nostromo, but different background.
2 They were workers on a planet that did mining, one of them was a pilot for the company and the space craft can't do 9 light years without substances and equipment the company controls extremely carefully normally (hence the trip to the abandoned ship/station) at least with a live crew, not to mention the whole thing the company that owns the spaceship also basically owns the planet and everything on it so normally any misuse of the equipment would get you in such serious trouble "security" for the space ship is not a question. IIRC the likes of large passenger aircraft in real life also have little in the way of anti theft measures, as the fact they're at a secured airport is enough (and the pilots can disable them enough to stop someone who doesn't know what they're doing from starting them). Even military fighter aircraft that are armed usually have at most a symbolic lock, as the real anti theft deterrent is the number of armed security around it.
3: The aliens come fast or slow depending on situation, they're stalking hunters a lot of the time when they are unsure of the threat level or are trying to be stealthy whilst their numbers are slow, also as you say they messed with gravity if you're unaware that's going to happen and get caught out you're very much stuck unless you can basically throw/squirt something or "swim" against the air.
4: fair, but that's often the case if you've seen enough films of a similar type.
a: IIRC you sweat to try and cool down as your normal skin cooling isn't enough, once you hit about 30c ambient you tend to struggle to cool down, so having the room at skin temperature is going to cause you to sweat as you and the room are now the same temperature.
b: I think I remember a couple of scenes similar to that from the other films, the alien doesn't always kill and will often prefer to injure/capture the prey alive to increase the hive, and in the other films that's shown to have given people a chance to do something.
c: a little lame, but a call back to Alien and one of the only ways you can kill/deal with a xenomorph without access to weapons - find a way to get the environment to do it (or at least incapacitate it). In Alien Ripley got it out the airlock and tried to fry it, in Aliens 3 they set an elaborate trap.
thanks appreciate the commentary. Maybe I need to watch the original again since its been quite awhile (I watched aliens just last week to get ready for this one). Makes sense what you said; next time I watch it perhaps I want be so judgemental and perhaps wrong on some of my assessments.