[Mr Rob]

I have a similar requirement. Here is my approach:

Create a "Waiting For" context.
Then create a sub-context under it for each employee.

eg.
Waiting For
> Bob
> Sue
> Sarah
> Tim

Set all of these context to "On Hold".

This means that any action with any of these contexts will not show up if your view option is set to "Available" - which is the pretty much the only view option I use except when doing my review.
(They will show up if you change the view to "Remaining" or "All")

This also means that they will not show up in Forecast view...
...unless you do one of two things:

1) set a due date on the action - in which case it will show in the forecast as a due item.
2) Set a start date on the item AND have "Days Show Starting Items" ticked in the Forecast view options.

So to answer a specific in your question - if it has a due date it will show in forecast and you can't get around that.
So I use the generally accepted best practise on due dates - only use them if it is a genuine deadline. That way I use the due dates to ensure forecast automagically gives me visibility of things I really do need to chase from employees.

Separate to the forecast view I have a "Waiting For" Perspective which shows all items with the "Waiting For" context regardless of availability, start date or due date - a one stop list of all the things I am waiting on from employees. I check this every morning first thing and if there is something on it that I want to action that day, or if I think an employee needs a nudge, I change the task from "Waiting For X from Tim" to "Chase X from Tim" and give it an active context...in my case "Office".

I hope that isn't too convoluted...and helps!

Rob