I think the youngest would be named Maurice or Robert, not Henry. Robert Charles is more likely for firstborn (Frederick Charles is a possiblity, after grandfathers, though). After all Rupert did name a DAUGHTER after himself OTL, so it's likely the same will happen with son.
Also, I think with Second Anglo Dutch War going better/William being restored in 1668/1669 England may well attempt to stay neutral in OTL Third Anglo-Dutch War, instead of being an active party to it, many of OTL goals of the Third War being achieved (and Mary being competing influence on Charles against Henriette).