New kit brings new choices....and change.....and based on my system....
1. The hard drive functionality will work but (if you refuse to embrace spotify
) it will leave your apps silent whislt the jukebox plays via the single audio output. The car's hard drive is not used by the apps etc as that kit has its own memory etc. The solution is to transfer your music files to your phone via itunes and play via car play,or to build a playlist within spotify or similar. You will not be able to use the USB stick as that port is taken over by the apple car play kit.
2&3 Dunno cos this is a technical question but my GUESS is that with this kit you have two separate systems and they dont mix. The kit keeps the car system totally stock,so if you dont switch to car play, you wouldnt know it was there. I dont think the maserati system can cope with splitting inputs - so the car mike input sticks with the standard system and hence a seperate mic input for the car play
Devonboy