The honest answer is no to both. A nice 1.5 DIN that plays mp3's would be an Alpine CDA-7998
Otherwise I think Pioneer has some fairly recent 1.5 DIN cd players that are no longer in production but easily found NIB old stock. I think the DEH-960MP is one? From what I recall I didn't think it matched our interior very well
CD Changer? You're correct in that you need to make sure the pinouts and plug types mate up but as far as I know the signal is the same. I highly doubt they utilize anything fancy like optical out but I honestly haven't looked into any of that. I thought the cd-changers were all built into the double din factory HU's these days? If that's true the question is moot.
