"The concept of agnosticism" was arguably created by T. H. Huxley... or at least he was the one who coined the term. My definition is in line with how he (and Robert Green Ingersoll, and Bertrand Russell, two other prominent agnostic thinkers) used the term. This dilution of the definition in informal usage to something like "I don't know" is relatively recent.
Sorry I don't think that is true. At least not from what I've read from these individuals. If you have a quote to back it up, I'll gladly change my opinion.
It was just strange because I would commonly make such a statement, and I've known others who would. Neither I nor these others were agnostic. Strange to know an agnostic would take such a religious position.
Russell's comments were something like it was impossible to know whether God exists at this time. Not that God is unknowable. It's not quite the same. It's more in line with we don't have enough information at present to make an informed decision on the matter.