The film feels very much like someone read the Gibson Alien 3 script and went from there, whilst the Rook/Bishop thing is almost straight from "Out of the Shadows" by Tim Lebbon.
The alien semi hive on the other half of the station - we only ever got told by Rook who was playing the humans in order to complete his mission that there was only ever the one live alien onboard (if he'd said "we had to abandon the other station" they'd have ran/done anything they could to avoid it), and whilst that was likely early on that's not to say there were not others later on but contained on the other half of the station.
Same with the frozen face huggers, there were IIRC 36 on ice on the half of the station with Rook and the dead alien, but what if those were just the samples that had been stored, with more samples that were intended for testing or even the research was being duplicated to some extent on the other half of the station (the whole Twins thing), or they were using the face huggers in some sort of testing.
Those sample holders could also have just held failed experiments that had been destroyed (although that seems unlikely). IIRC having the "dangerous" work done in one facility and the "clean" work done in another would make sense given the station design (theoretically fairly easy to isolate/control what moves across by the looks of it), ties in with the way Wayland Yutani has been shown to work in canon (often hiding the nasty stuff from the normal staff who might panic/tell the authorities/try to stop it), and also mimics a lot of real world research projects where the macro scale work might be done in one building and the micro scale in another, as the risks/needs of the two are different, it also means you can store the successful frozen samples away from any non frozen much riskier samples that you might using.
We also know that IIRC even a "drone" can create eggs, IIRC that's canon in the films and the books (I think it's in the Alien book and might have been filmed/cut from alien) as a way for a lone, isolated alien drone to create a hive, the Queen basically comes along when there is the potential for a full hive in order to provide the eggs for it and results in the creation of the other types of alien such as the warriors and workers. The drone is basically a jack of all trades including egg creator but it might take weeks to do what a Queen can do in a day. So if the lone alien managed to escape for any length of time there is the chance it could lay/create at least one egg.
With reference to the speed of the alien growth, in the official books there is a lot of suggestion/outright claim that the aliens can control how fast they reproduce/grow to full size - they are already known to basically be able to survive almost indefinitely and in almost any environment, which means they have to have some control over their metabolism. Basically they can grow faster or slower depending on what works best for the conditions including external threats* (IIRC even in the films the time from impregnation to bursting varies).
In the films with the exception of Romulus we've never IIRC had a definite timeline for how long the entire thing has taken, Romulus lets us see it happen in the space of a day, Alien shows us the impregnation, and Kane going through the burst potentially only hours later and no definite timeline between that and the full grown alien - except that it probably happened in under a day.
Basically my take on the extra huggers and drones is that either they were doing experiments on the other half of the station, possibly the "live" ones with active facehuggers and a drone and it fell apart, but they managed to largely contain it, whilst the half Rook was in was the more advanced/less risk of escaping experiments (they moved the frozen huggers over, and did the microscopic and modified dna work there), or the drone was active over there for long enough to either create eggs, or damage a facehugger storage or disposal facility.
For reference the Alien recovered to a space station for genetic manipulation was largely the basis for the Gibson Alien 3 script set after Aliens, and also included it affecting other species such as the rat (IIRC in Romulus you see something happening to the lab rat that was "safe" for a fraction of a second, and the remains of possibly the same rat or an earlier one), and humans in a way that is very similar to what happened to the foetus/baby. Whilst the very rapid change from the "infection" is from Gibson's A3 script and IIRC promethious (one of the reasons I didn't mind parts of Promethious so much was that it did tie in to GA3).
*In the books/films the aliens are meant to be able to communicate with pheromones or something similar to some degree (as well as some sort of psychic link), so potentially the embryo/chestbuster could be triggered to grow fast if there is plenty of food or a higher risk.
