"Deloading" the bar onto the ground in between reps, for rows, is called JS Rows. I would use those.
A deadlift is called that because you're lifting a dead weight. So yes the bar would be completely stopped and on the ground before doing the next rep.
Refer to the injury sticky for your hamstring. It depends on the severity, if it truly was a strain then I would've stopped squatting and iced it.
*Edit* When I hit the 'first new post' button it brought me to the bottom of page 1, so I didn't see the posts on page 2
