Am I limited to just the choices listed in the multiple choice dropdown?

    Nope. You can type in any value you want. Plus, if you want a 'blank' for the answer, there is always a blank line at the bottom of each multiple choice list. 

    Speaking of 'blanks,' if a multiple choice variable demands a 'blank' answer, you can create one in any spot in your multiple choces by simply putting an unadorned slash at the desired position (including the first position). (This is particularly useful with 'grouped' variables where the selection of an item in one member of the group leads to a 'null' selection from other members of the group. E.g., [!c!no children/one child/two children] . . . [!c!// , or either of them].