Rear Backup Sensors Questions

I'm strongly considering getting the rear backup sensors added to my tech/ent. The backup camera is nice, but I'd like the sensors, too.

When the sensors are added as accessories, and an object is detected, does the nav screen show where the object is located?

Also, I'm a bit concerned with the dealer installing these since much of the inside of the car needs to be taken apart. For those who had the sensors installed, did the dealer do a good job putting everything back together?

Thanks for any input.