well he sounds just like my boy, Spirited! and Caleb did the same things at wind down that yours does, it used to throw me for a loop! what we found at this age is that less wind down was better, so a quick story, quick cuddle, say phrase and into bed.
I would try darkening your room even more, with even a small amount of light Caleb just cant shut off, he gets distracted by something and wont go to sleep, hes better now but under 12 months old it had to be pitch black in his room. It does sound like he could be teething though, have you tried giving pain meds once before a nap to see if that makes any difference? I would try about 20 mins before a nap so that if he is in any discomfort that should be gone by the time hes due to sleep.
If he doesnt cry, I wouldnt go into him at all. although I did that once and he chatted for 45mins before I just eventually got him up, still if hes happy then leave him. I know hes not sleeping and thats what you want him to do but give him a chance to fall asleep by himself, he may surprise you! if not then you know thats not an option for the next day.
For your first A time it is quite low, it is possible that hes going to nap UT and then ends up OT by the next nap. Try extending his A time in 15min lots every 3 days and see if that helps