As per usual, don't copy Google if you don't have the same requirements. Google Search never goes down. HN goes down from time and nobody minds. Google serves tens (hundreds?) of thousands of queries per second. HN serves ten. HN is fine with one server because it's small. How big is your service going to be? Do that boring math :)
Correct. I like to ask "how much money do we lose if the site goes down for 1hr? a day?" etc.. and plan around that. If you are losing 1m an hour, or 50m if it goes down for a day, hell yeah you should spend a few million on making sure your site stays online!
But, it is amazing how often c-levels cannot answer this question!
