calcium carbonate is still basic and even hydrogen carbonate is basic enough to be protective against steel corrosion
The Calcium Carbonate once dissolved in water will start to form the Calcium Hydroxide layer on the surface, thats the alkaline layer, and deeper in the carbonation creates acidity.
100% wrong, how come there's more carbon dioxide inside than outside, you're starting from calcium hydroxide and silicate. on the surface there's some carbonate formation from carbon dioxide, but when it can't get there calcium silicate forms instead. either way both are basic
there are also more damage-susceptible things in a datacenter