Erik Reinert's conclusions and experiments in economics
It's been too long since I read those, so I don't exactly remember  whether they answer your two specific questions, but if you are interested in the topic you should definitely have a look at:


https://en.wikipedia.org/wiki/The_Bottom_Billion
https://en.wikipedia.org/wiki/The_New_Bottom_Billion


and the corresponding TED talk at


http://www.ted.com/talks/paul_collier_shares_4_ways_to_help_the_bottom_billion?language=en