Yes, with no previous context or warning I would assume the same, but regardless, the notation exists.

Might be. I've never seen it used that way, though, I know that some people prefer parentheses around the fraction to the right of integers.

I learned at grade/primary school, it's useful as a teaching tool for fractions. Although, I do recall using something similar for partial fractions in college.

That said, even Wolframalpha appears to disagree, which I find mildly funny if what you say is true.

In wolfram alpha they call it mixed fraction or number.