The more i think about this book the more i like it and its take on Hicks.
All the mutations are easy to explain and the book hints at it.
Spoiler
LV426 was the aliens' first "meeting with mankind"... and the more they "use us", the better they get at finding ways to "reproduce" with us (with each generation).
Queen was already creating a new generation of aliens with new skills over at Acheron before Ripley destroyed her.
When the Queen attacked Bishop, genetic material from this new superior generation got implanted within him....
and things got out of control from that moment on.
The whole last third seems to work as this mini morality play with Hicks figuring out the role that lying (to self and others) plays in keeping hope alive.
Spoiler
When Hicks lies about the timing of the station blowing up
And considering Cadigan's personal history that theme.. feels a bit poignant.