As the "Bodysnatcher Collection" is currently unavailable (and was never released in America anyway), I've volunteered to summarise Rob and Doug's thoughts on the genesis of the characters and their approach to writing the show. Well, I say summarise - this somehow turned into an essay. :p
(If you're wondering what I'm talking about, this very long review describes the product in question:
http://www.ganymede.tv/indepth/red-dwarf-the-bodysnatcher-collection-review)
Mods: Sorry if this seems OT, but there are references to slashy bits in "Bodysnatcher" and "Dad" which I think makes this relevant to this community. :)
http://janamelie.livejournal.com/8561.html