Filter content types based on folder properties

Given:

1. some Content Types with "categories" multi-value property (sample values are: "legal consulting", "accounting consulting");


2. some folders each one with a single value "category" property

User creates documents from Word: how could I filter the Content Types available for that folder, filtering the Content Types whose "categories" include the folder' category?

UPDATES according to suggestions, Document Libraries are the way to go. But are they searchable by the Word File Dialog interface? I mean, could the user search for a specific DL by its name? (and not directly searching the document name itself)