Your sentences green importantly, so addition commutes alike? Thusly---there you go.
(In other words: you're not making yourself clear.)
So what? And Pi is a place holder for the diameter-to-circumference ratio of the circle. It remains true that mathematics has gotten beyond this, and for example the equation "e^(i pi) = -1" is true despite its total disconnect from circles and circumferences. Likewise, mathematicians now (and 500 years ago) know much more about zero---and about all numbers, and about non-numbers and functions and operators and whatnot---than ancient merchants did.
The history of mathematics is interesting, but the truth or falsehood of math statements is independent of their history.
You are again not being clear. Give an example.
I only bring up the history of math to prove a point that, as illustrated by other posters, who are trying to measure the voltage of a table, that most persons do not have a good concept of what zero actually is. Physicists have not made that great leap into the acceptance of what a good mathematician can do with zero. Hence why I bring up absolute temperature, and departing into the different algebras.
As far as infinities of different sizes her's a good article http://www.sciam.com/article.cfm?id=strange-but-true-infinity-comes-in-different-sizes