[Ken Case]

I don't think the web app has any mechanism for only viewing items with due dates assigned.

You could place all those items in an on-hold project and move them out as you figure out when you want them to be done, or you could assign a future start date on tasks so they won't become available until that date. (You can set the start date on multiple tasks at once by selecting them all, then pulling up the Inspector and using it to assign a Start Date to all of them.)

Hope this helps!