A peer-reviewed article is published in a peer-reviewed journal only after it has been subjected to multiple critiques by scholars in that field. Peer-reviewed journals follow this procedure to make sure that published articles reflect solid scholarship and advance the state of knowledge in a discipline.
In baseball, a walk-off home run is a home run that ends the game. It must be a home run that gives the home team the lead (and consequently, the win) in the bottom of the final inning of the game. Thus the home team can walk off the field immediately afterward, rather than finishing the inning. The winning runs must still be counted at home plate.
I always thought it was a baseball term. Right off the bat means actions happen right away on contact. Runners are in motion, right off the bat. It can be applied as well to anything as soon as one action is completed, a chain of events occur too.