In my newly acquired 1984 home, the clothes dryer duct run is square duct not round duct as I would expect. There is a round hole in the side at the floor for connecting to the dryer exhaust.
1. Are there things I should know when working with/using a square duct for dryer venting? More/less efficient? etc
2. The bottom of the existing duct runs to the foundation, but the wall connection for the dryer exhaust is above the foundation by a number of inches. So just below the wall connection, inside the duct, there is essentially a reservoir into which lint and waste can collect. Is there a way to remedy this?

-Troy