Learn Farsi: پدرم در ایران است.

Yes! For physical locations like being inside a country or a city, dar behaves exactly like the English preposition "in". You just place it right before the location, exactly as you do in English: dar irân means "in Iran".

I see "my father" is written as a single word, pedaram. How does that work?

In Farsi, possession is usually shown by attaching a short suffix directly to the end of the noun. The word for father is pedar, and the suffix for "my" is -am. Joined together, they make pedaram.

Why is the word ast (is) at the very end of the sentence?

Farsi follows a Subject-Object-Verb word order. This means that the verb almost always comes at the very end of the sentence. Here, the subject is pedaram (my father), the location phrase is in the middle, and the verb ast (is) completes the thought at the end.

Will I always hear native speakers say dar in sentences like this?

In written or formal Farsi, yes. However, in casual everyday speech, native speakers often drop the word dar completely when talking about locations. You might just hear someone say pedaram irân ast (or even pedaram irâne in very relaxed speech), and the "in" is simply understood.