Our 2019 car is very wonky when using the GPS sync. The clock DOES lose it's time when starting up, and other things are wonky as I recall. What WE do is disable GPS sync in general, but if the times change or the clock gets a couple minutes fast/slow, we enable GPS until the clock corrects...
I swapped my factory radio out for a Kenwood many years ago (there's posts somewhere here, but I'm away and don't have the links). I reused the factory camera with a voltage adapter and it works fine. You will need other adapters through to reuse the steering wheel controls etc.
You do lose...
Not sure I understand? Premium gas will also contain alcohol (unless you specifically get a gas that is advertised as zero alcohol, but that's not available at most gas stations).
Not 100% sure about this, but worth a try... just adjust the volume on your phone while using the assistant. That should work, and is probably easiest.