Yes we are
Yes and no. You teach how to solve equations, but not the fundamentals (and if you do then kudos to you, as it's not a trivial accomplishment). Fundamentals, most of the time, are taught in universities. It's so much easier that way, but doesn't mean it's right. People call it math, which is fair enough, but it's not really math in a sense that you don't understand the underlying principles.
Yes there is!
Nope.
There's only commutation, association, distribution, and identity. It doesn't matter in which order you apply any of those properties, the result will stay correct.
2×2×(2-1)/2 = 2×(4-2)/2 = 1×(4-2) = 4-2 = 2
As you can see, I didn't follow any particular order and still got the correct result. Because no basic principle was broken.
Or I could also go
2×2×(2-1)/2 = 4×(2-1)/2 = 4×(1-0.5) = 4×0.5 = 2
Same result. Completely different order, yet still correct.
My response to the rest goes back to the aforementioned.