Absolutely! In OTL there were not even two centuries of relative openness between east and west, before the Parthians and Romans erected millennium-lasting iron curtain. And by them, even once the Muslim conquests kind of opened the way back up, it was too late as western philosophy became firmly rooted in Christianity. In this TL, if all goes well, there will be at least decades more contact with even India. Lots of room for influence.
Yes. His own Wikipedia page doesn't mention relation to the Seleukids, but some other page (Seleukos's own, I think) mentions Diodotos satrap of Baktriane as being his nephew, so I decided to keep the relation. In this TL results may vary on forming his own kingdom.