+1 on Lexol products. They work great, I've used them for years. All automotive leather has many layers of dye, polyurethane and UV/stain protectants. It is actually pretty tough. Your biggest threat is dirt and dust that can grind in and wear the coatings. Just keep it clean and you should be fine.
The top view "camera" is a computer generated image based on the front, side and rear view cameras. There is a good change that the wires are there, but adding all the cameras and updating the vehicle software would be really tricky. Maybe these guys can help you: www.bimmer-tech.net/shop
The remote APP I have only unlocks doors, flashes the lights and honks the horn. It's more of a novelty than a useful tool. Maybe there are other Apps, but I doubt any of them can start the car. BMWs scrolling key code technology does not allow for remote starting.
There is no need for multi-weight oil to warm up before setting off. Just don't drive aggressively until fully warm. Same rule applies in hot weather. Besides I lived in the UK for a couple years. You don't know what cold is.
Hope this helps.