I used to have a MK1 GT Cortina in the early seventies, it had lovely black PVC seats.
They came up lovely with a bit of Pledge, lovely smell, and good for removing most stains 😜
Interesting predicament 😃
I'm not sure if there is a means of tracking the key fob, but someone will surely be along shortly to tell us.
My advice would be to completely search the car from one end to the other and I'm sure if it's there you will find it. Maybe you've already done this ?
There is an option on the settings to have the radio volume change to suit road noise Melissa, but you can untick it if you wish.
I'm not sure about the sunroof as I don't have one.
The steering query certainly does not sound right as even with electronic steering going from very tight to very loose is a dangerous phenomenon.
Other posts will confirm this Melissa.