In regards to your point #2. I just replaced the first one with a generic one off eBay. It turned my cel off and my car is driving fine so far. Why would you only trust one from the dealer? Is there a predicted issue I should expect?1- Yes 19$ in ebay. I even order another one as spare
2- the second one, after the cat. $ wires o2 sensor. For the first one, I take no chance. Dealer only.
3- mine is also a 2000.