1.) It's too poetic for your usage. Better to say 'untested' or 'unfamiliar', i.e. rather than to unfamiliar foreign countries. 2.) Yes, your idea is correct. 'Internationally, challenges include, A, B, C and D. 3.)You need a comma after 'economies', especially as the subordinate clause is so long. 3.) You are correct that 2 things require 'have' and 1 thing requires 'has', but it is part of the richness of the English language that we can use either giving different emphasis. Using 'has' essentially unifies the two things in the mind of the listener. So both are valid here with a slightly different meaning.