Questions & Answers about Millainen mies hän on? Hän on komea.
Is there any difference between millainen and minkälainen in this context?
Both millainen and minkälainen mean "what kind of" and can be used interchangeably here. Millainen is generally more common just because it is slightly shorter, but grammatically they act exactly the same.
Do millainen and the noun it modifies always have to be in the same case?
Yes! Millainen functions just like an adjective. Because mies is in the basic nominative case here, millainen must also be in the nominative. If you were asking "In what kind of man...", both words would change to match: millaisessa miehessä.
Why is komea in the basic nominative form instead of the partitive form (komeaa)?
When a sentence follows the "A is B" structure, the adjective describing a single, countable person or thing stays in the nominative case. You only use the partitive case for the describing adjective if the subject is an uncountable mass or an abstract concept, like water or weather.
Finnish pronouns don't have gender, so how do we know hän translates to "he" here?
You are right that hän can mean either "he" or "she" because Finnish does not use gendered pronouns. We only know to translate it as "he" in the second sentence because the first sentence provides the context that we are talking about a mies (man).