Learn Farsi: گزارشگر با صنعتگر صحبت می‌کرد. - The reporter was talking with the craftsman.

The suffix -gar is attached to nouns to indicate a profession or someone who does a specific action. Here, it is added to the noun gozâresh (meaning report) to create gozâreshgar, which means reporter.

Could I use the suffix -kâr instead of -gar to make san'atgar (craftsman)?

No, while both -gar and -kâr create profession nouns, they usually attach to specific words and are not interchangeable. The word san'at means craft or industry, and san'atgar is the established word for craftsman. Saying san'atkâr would sound unnatural.

Why is the prefix mi- attached to kard in sohbat mi-kard?

This is a helpful refresher on the past continuous tense. Adding the prefix mi- to the simple past verb (kard) shows an ongoing action in the past. While sohbat kard just means talked, sohbat mi-kard specifically means was talking.

In English we often say talking to someone. Can I use beh (to) instead of bâ (with) in this sentence?

In Farsi, the compound verb sohbat kardan (to talk) almost always takes the preposition bâ (with). Using beh (to) in this context sounds unnatural to native speakers, even though it translates perfectly well in English.