Learn Turkish: Kırık mı kırık bir sandalye.

This is the exact structure we are learning: Adjective + mI + Adjective. Repeating an adjective with the question particle in the middle is a common Turkish way to add strong emphasis. Instead of asking a question, kırık mı kırık means "completely broken" or "broken beyond belief."

What is the difference in feeling between saying çok kırık and kırık mı kırık?

Çok kırık (very broken) or tamamen kırık (completely broken) are standard, factual descriptions. Kırık mı kırık is much more expressive and conversational. It adds a storyteller's flavor or a sense of exasperation, really drawing the listener's attention to just how ruined the chair is.

Why is bir placed after the long adjective phrase instead of at the beginning like in English?

In Turkish, the indefinite article bir almost always sits directly in front of the noun it belongs to, following any descriptive words. The rule is [Adjective] + bir + [Noun]. Here, the entire emphasized phrase kırık mı kırık acts as one big adjective, so it must go before bir sandalye.

Does the particle mı still follow vowel harmony in this emphasis structure?