Hello,
You said that top and middle management must make ethics a priority and exhibit ethical behavior, but how is that possible when an employee has something to blow the whistle on? In my view, if management made ethics a top priority, wouldn't that remove the vast majority of reason for someone to be whistle-blowing in the first place. Employees follow the lead of the leaders, and if the top levels are exhibiting ethical behavior and appropriately hiring others who would do the same, the actions would seem to cancel each other out.
Regarding retaliation, I believe much of the same is true. While there can be rogue employees who may take out their anger or issues on a whistle-blower, if management from he top down is encouraging reporting misconduct and expressing a need for accountability, then when these issues come up, wouldn't everyone else tend to fall in line with the leaders. I think the easiest way to prevent misconduct, and therefore the ned for whistle-blowing, is to have strong leadership at the top who enforce a sense of ethics on everyone below them.