I'm having trouble understanding this translation. "russia is this country" seems right to me?
No, in «X is Y» questions «э́то» is used in place of «is». For more info, see the guide to using э́то by olimo here: https://www.duolingo.com/comment/11536858 and my comments here: https://www.duolingo.com/comment/11559427
«Russia is this country» would be «Росси́я — э́то э́та страна́».
I read the two links you cite which are helpful. I realize from them that "Russia -- this is a country" would not be the standard translation, but is it acceptable (or: does it make sense)? Is there a different way to express that?
Is it okay to say "россия страна", or does that leave to much vagueness as to wheher the sentence means "Russia is the country" or "The country is Russia" ?
You can say that and still be understood, but it's better to use the это since it's a definitive sentence. Russia IS a country.
Is there a meaningful difference between "country" and "nation" (which got me dinged)?
«Россия — эта страна» means "Russia is this country". This can work in some contexts, but it means a different thing.
Please see the guide by olimo: https://www.duolingo.com/comment/11536858