Glad you brought up #3 - it was the not prime cause for the Depression but it made it last as long as it did. Read:http://americanhistory.about.com/od/greatdepression/f/smoot_hawley.htm
Yes and Amity Shlaes discusses this in her book “The Forgotten Manâ€.
This seems to be a common perception here, that a “trade war” would erupt which would somehow hurt America because our trade balance would be impacted.
Smoot-Hawley was when American built things for the entire globe.
Now the situation is reversed. The only thing which would happen today, is we would need to rebuild American industry.
Which we should be doing. Now IMO.