I personally don't like the look of the camera footage. I really like having rich colored, high resolution cameras so the sentry mode experience is better.
Actually you are comparing Gen1 seats with Tesla premium but a seat existed in 2016 that was made by Recaro and is Tesla's best seat: the next gen seat and it's very nicely bolstered and has real leather. Definitely better than Tesla's first attempt at seating.
I LOVE my next gen seats. Very, very comfortable! And to answer the OP's original question, yes, you can go from 2.0 to 3.0. I just had it done. Personally the camera's are a non issue for me. Plenty high enough resolution to be able to identify traffic incidents and the dreaded sentry mode event.
Cars built from October 2016 through July 2017 would be AP2. Beginning in August 2017, they started using AP2.5 hardware which included cameras with improved color. Many of us have had no problem buying cameras directly from Tesla and upgrading our AP2 cars. You can also find them for sale on Ebay. Shop around though and get quotes from Tesla. Sometimes the cameras on Ebay are a deal. Other times they are a rip-off. You should be able to find answers to all of your camera questions in Upgrading AP cameras
For the visual folks (see below). I did upgrade my repeater (fender) cameras but it was a little challenging (post: Upgrading AP cameras ). Graphic and hardware explanations. Autopilot, Processors and Hardware – MCU & HW Demystified – TeslaTap