Issue in Rear Camera application

If the phone is still under warranty, and after examination by the Genius Bar and it is felt to be defective, they will replace your device with one just like yours, same size, color, etc. They have warranty replacements on hand.

Warranty devices are in stock as I indicated earlier. Warranty replacements are generally refurbished devices. For your second question, you will get back what you brought in. Warranty exchanges are in-kind. You get back what you had. If you wanted a different color device, you would have to sell your current phone and purchase another.

Apple does not do repairs, they replace. Again, if they determine it is a warranty issue, they will replace the device. You will not be able to tell the difference between a new phone and the refurb. They are tested and inspected closer than the new phones are.

If Apple Care is offered in your location, you would need to check. Apple Care + cannot be purchased more than 30 days after the device is sold. Apple Care may not be offered where you are located, so you can check into that. Price is location dependent.

You will need to make an appointment at the Genius Bar of the Apple Store. When you come in for your appointment, they will examine the device and if it is in need of replacement, it will be exchanged right there.