Landry is the latest coach to follow Matt Campbell from Iowa State.
Walker was Penn State's assistant running backs coach for the last four seasons.
Rosa played at JMU and Central Connecticut before moving to Happy Valley.
Ford appeared in 26 games as a Nittany Lion and totaled 31 tackles, 4 tackles for loss, 0.5 sacks, and one interception.
Another Nittany Lion heads down to Blacksburg.
Huggins completes the first core staff of Matt Campbell's Penn State tenure.