DropDownBox items from cookie

I have a page that has a DropDownList on it. This dropdown needs to do a few things:

1 - The user should be able to type in a value or pick one from the list. How do you set the dropdown properties to do this?

2 - The items listed in the dropdown need to come from values stored in a cookie. I know how to do this from a DB but I never did loaded one from a cookie. How do you do this?

3 - Lastly, if the user decides to enter a value instead of picking one from the list, the value they enter should be appended to the current cookie so it shows up in the list the next time the user visits the dropdown.

ANY tips, code, or resources would be GREATLY appreciated!!

ps: I'm developing in .NET but any ASP code would be fine.....

Thanks!!!
~Piz