Your question is kind of hard to figure just what you are wanting so I will take a stab at it and might even come close.
A user goes to a form on a page that has several fields that they may or may not fill out that point to a list of terms or perhaps topics with each one of them having a checkbox.
After the user selects at least one of these checkboxes then the topic or term selected will then display allcontent associated with that term or topic. Is this right or am I completely missing the point?
Do you perhaps already have a script where people could maybe see just what it is you have where suggestions could be made to help you make it work? Or do you want someone to offer a script to attempt to do what it is you are wanting to do?