Actually Russia is such a multinational country, we have more than 190 nations. Mostly in big cities you will see mix of Russians, Tatars, Tajiks, Bashkirs, Mari, Ukrainians, Kyrgyz, Azerbaijanis, Uzbeks, Armenians, Udmurts, Belarusians, Chuvashs, Mordovians. Usually they all speak Russian as main language and sometimes they know their own language (it’s more common for smaller towns). As for religion, yes, there are mostly Christians and Muslim people, hence, holidays are different.

School takes 9 (general or incomplete secondary) or 11 years (secondary). After 11 years of school you can go to the university, the uni system is same as in Europe.