I actually use both apps, I find Organic Maps a lot nicer for looking at a map and navigating by foot or bike, and Magic Earth seems to pick more sensible car routes some times. Also the live traffic data makes it more fitting for car navigation (Organic Maps doesn’t have traffic data).

I can highly recommend Magic Earth as a Google Maps alternative (also available for Android). It uses OSM data and has some traffic info. It’s not as good as Google, but it’s the closest I’ve found so far.

AFAIK you can enable the snapcast server and then use an app like SnapCast to stream to your mobile devices.

The newer Sony Xperias sound like a good fit for you. I haven’t used one myself, but they’re pretty decent from what I can gather.

Also it seems as if Sony is the only phone manufacturer shipping flagships with headphone jacks and SD card slots.

On another note, I highly recommend the GSMarena Phone Finder for getting a general selection of phones that have the features you care about.