Earlier quoted context omitted.
Classifiers are mostly orthogonal to the number system, and they're really no different from e.g. English using "a herd of cattle" or "a murder of crows" to redundantly encode the kind of thing being talked about. I'm actually not aware of any language that doesn't have different units of measurement for different objects, it's just that some languages effectively make it mandatory to use them. (E.g. in Chinese you c…
Yes, they are different from English. In English you say "one herd of cattle", "two herds of cattle", and so on. You just need to know a plural of "herd" and the regular numbers. In Japanese the numbers themselves depend on the counter. You can't say "one day", "two days", "three days". You can only say "one day (ichinichi)", "foobar (futsuka)", "bazbar (mikka)", and so on. And this counting system is used pretty muc…
The situation is similar to Latin or Greek numerals in English, which are also applied pretty inconsistently. E.g. duplicate, triplicate, quadruple, ... but pair, triple, quadruple, ...
In general, all languages are riddled with exceptions, ambiguities, contradictions and archaic forms, but it's easier to notice them when you're learning the language later in life and have the "logical" structures of your mother-tongue to compare them to.