It sounds like he's doing really well! My ds was always a "learner"...but I definitely noticed that the things they did at school would spark an opportunity at home (made a "cave" in his bedroom for nocturnal animals after they discussed this in school for example).
My suggestion is to follow his passions and make learning fun. What my ds says he misses most now that he's in school full time is the hands-on things. Field trips, nature walks, science experiments - makes me half-wish we were homeschooling.
Thanks! yes, I have always just followed his lead. I can't even come up with the stuff he does so I don't have a choice! lol I purposefully pushed for AM preschool class so we would have the afternoons for trips and other activities.