Apparently the words “Iran” and “Aryan” come from the same Indo-European root meaning, more or less “The Tribe”. Clearly the Iranians are Indo-Europeans and therefore Aryans, unlike the non-Indo-European Finns, Basques and Etruscians.
Yup. The word for almost all peoples in their native language translates to some approximation of “The People,” with implications that all others aren’t really people.
Most Europeans, Iranians, Kurds, Afghans and Indians are Aryans, though Hitler would no doubt have balked at including many of these groups.
Notably all Slavs are perfectly good Aryans. Why the Nazis chose to exclude them makes even less logical sense than the rest of their racial doctrines.
Languages get spread across racial divisions very easily through conquest, trade, etc.
Half the population of Iran is not Iranian, but Arab, Kurdish, etc. Persia changed its name to Iran in an attempt to capitalize on the "glamor" of the "Aryan" theme.
The racial theories of the National Socialists were pure pseudo-scientific crap, just like other doctrines of various flavors of socialism. Although the Nazis demeaned Slavs and glorified Nordics, there is a heavy Slavic component in the German population, and Germany is far from being the most Nordic country in Europe.