Both issues still happening despite switching to Apple Wireless CarPlay and having nothing at all plugged into the USB data port.
But I now have both on video
1) Start the car and all I get is a blank infotainment screen - the video was taken after I had started the car, put my seatbelt on and still had time to get my phone out and take the video. Completely black screen for over 30 seconds before the menu suddenly appears. The same issue What Car? magazine had with their own long term Jazz:
2) Even though phone shows available, you can't connect. Same issue either at start when the phone doesn't connect automatically or manually or sometimes it drops when you are driving, losing carplay and won't manually reconnect until some random time later it may start working again: