Just a though Nato.... I don't know if the paint is a close match, but if you want some additional cars, you might try to find some of the Rapido "Panorama" cars made 10ish year ago (with a couple of additional releases). The caveat is that they have body mounted couplers and mixing them with the Kato truck mounts (I am assuming the current production is equipped with these like my older Katos) can cause some operational issues, as I am sure you know.
The Rapido cars are all models on CN prototypes- coaches, "daynighters" (ie- rebuilt coaches), cafe-bar-lounge (which were also rebuilt coaches), 10-5 "Bay" sleepers, 4-8-4 "E series" sleepers, and a CN baggage car. They also did some "stand in" Osgood Bradley coaches in CN colors. Unlikely to find any in hobby shops, but they do show up on eBay and "yard sale" sites or on N Scale Supply's used equipment listings.
That said, if the Kato sets sell well, it would certainly not be unlike them to bring out a 2 or 4 car add on set, as they have done with some other sets in the past.
On the spacing of Kato F units- its been an issue since they first came out in the late 1980s. The unimates mentioned by altohorn25 are the most common solution.