this is, in my opinion the most important
in a category , it should be possible to assign personal fields in a topic, so when a user starts a topic he could choice a particular value in a combo.
The values of personal fields will be shown in their respective columns in the forum.

This feature permits to add many many possibilities eg: in an category of cars, an user can post his topic and choice a brand for his car. So the topic list will show all posts and the brand. Without this feature many subforums should be created, one for each car brand.

Or in a category for customer assistance , a user can be choice a level of urgency for his tickets, his product , and patch version

The formulation of your idea might not be perfect, but the idea is pretty good and would be a quite innovative feature if the user than could select which topics he want to see. The other topics could be made invisible, with hidden div's I guess (I mean like you can hide the moderators in Forum control in the new ACP of v.2.1).