"There are few new roads in poor countries."
Translation:A szegény országokban kevés új út van.
No, but it becomes a very general statement without it. Sounds like "Poor countries have few roads". Almost like a definition.
That's also what I understood from the original English sentence. It applies to every poor country.
Yes. The difference is small. You could also add "the" to "poor countries". And you could state a fact, or you could make a statement about the usual characteristics of poor countries.