I think the NW (night wakings) are being caused by not enough sleep during the day.
I personally would extend his morning awake time a little bit, just by 15 mins or 5 mins depending on your LO.
his 2nd nap however is spot on!!!2hrs is great
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I would say that he is getting ready to drop that catnap and most LOs will do that at this age.Again this another reason they will need some of their awake times adjusting as they will be only having 2 naps now.
With the night feeding I wouldn't consider it that unusual for him to be feeding once during the night even at this age.some do take a little longer to drop their night feed.Do you feel he is genuinely hungry or is more for comfort and getting back to sleep?
He is at the right age for starting solids and at this point you would still offer the BF first and then solids.Start with 1 mealtime (i did dinner with sasha but most people will do lunch) and gradually build it up to 3.I'm going to get the solids mod to just post a few tips as shes far more an expert than me!!
HTH