Awesome tips!! The war museum in Kiev sounds like a perfect match with their interests. I am sorry I missed it myself when I was there, but I am planning to return to Kiev some other time, so I guess I'll have to check it out then. The Stalin line sounds cool too.

As for Minsk, I noticed myself that there were was a big war museum at the Independence Square (I did not visit that either!) As for Soviet stuff, there were some monuments around, and a metro station with a Soviet theme.

As for nightlife in Kiev and Minsk - well I am not going to give them any tips on strip clubs! If they want to find that, they'll have to do it themselves.
But if you know of a nice sportsbar, or something like a pub, then I'd pass it on.. Do you know any?

My friend speaks no Russian and he did not mention that his travelling buddies do either, so my guess is no. Other than Swedish, they speak English and German. I warned him that neither is massively useful in Ukraine or Belarus. But he is super excited about both Ukraine and Belarus and is prepared to take a risk!