Learn Farsi: دستان و بازوان او خیلی قوی هستند.

You are right that -ان is generally for animate nouns like people and animals. However, in formal or literary Farsi, paired body parts (like hands, arms, eyes, and lips) are a special exception and often take this suffix. In everyday spoken Farsi, you would still normally hear دست‌ها and بازوها.

Why does the plural of بازو (arm) have a 'v' sound in بازوان?

When a Farsi word ends in a long 'u' vowel like بازو (bâzu), adding the plural suffix -ان (-ân) creates a vowel clash. To make it easier to pronounce, a 'v' sound is inserted as a bridge, making it بازوان (bâzovân).

Why is the verb plural (هستند) when body parts are usually treated as inanimate objects that take singular verbs?

There are two reasons here. First, combining multiple nouns with و (and) often triggers a plural verb. Second, using the animate plural suffix -ان gives these body parts a more 'living' or poetic quality in formal Farsi, which strongly attracts the plural verb هستند instead of the singular است.

Where exactly does the ezâfe (the linking 'e' sound) go when we have two nouns connected by 'and'?

The ezâfe only attaches to the final noun in the list right before the possessor. It sits after بازوان, linking it to the pronoun او. You pronounce it as 'dastân va bâzovân-e ou'. You do not put an ezâfe after .