This is irrelevant, because it only applies to life-threatening injuries, whereas the author is discussing patient injuries in general. This pre-existing policy doesn’t tell us anything new about why overall patient injuries have decreased with the new monitoring plan.

This weakens by making it more likely that there is an alternative explanation for the decrease of patient injuries that is unrelated to the consequences of the plan. After all, the other hospital saw the same outcomes without the plan as a possible cause.

This is irrelevant, since the argument already tells us that the plan specifically records staff errors that do cause patient injuries. This doesn’t help us figure out whether the plan was the true cause of the decrease in injuries.

This strengthens the author’s hypothesis by more closely correlating the staff’s knowledge of their being monitored with the decrease in patient injury, making it more plausible that the former is a direct cause of the latter.

Without more information, it isn’t clear how the plan’s policy toward reprimanding or otherwise punishing staff members might have affected the incidence of patient injury, so this doesn’t give us more reason to believe that the plan succeeded.