Should I use the preposition "in" with the names of languages in these sentences?
Do you speak in English or in Russian with your teacher? Or Do you speak English or Russian with your teacher? Can I also say "Do you talk to your teacher in English or Russian?

Question

Answer

The right verb is speak while talk is used for short duration of time the difference between speak and talk is in duration

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@Mohamed - "in" is required for the common case of speaking/talking about a topic in a language.

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The Oxford Learner's Dictionaries are an excellent resource.
https://www.oxfordlearnersdictionaries.com/definition/english/

The basic patterns are
to speak (a language)
to speak (to/with someone) (about something/someone) (in a language)
to talk (to/with someone) (about something/someone) (in a language)

speak
https://www.oxfordlearnersdictionaries.com/definition/english/speak_1?q=speak

meaning 4
​[transitive] (not used in the progressive tenses) speak something to be able to use a particular language
to speak several languages
to speak a little Urdu
Do you speak English?

meaning 5
​[transitive, intransitive] to use a particular language to express yourself
speak something What language is it they're speaking?
speak in something Would you prefer it if we spoke in German?

Answer

You don’t need to use in in the question keep it simple and straightforward