RE: I would like to be able to have a basic search facilty (using just keywords) on each of these pages which would only search the appropriate category.
Assuming you are using cMap with those shortcode options, the key word search should be limited to the chosen category. If the entries are added to multiple categories and it exists in
category=2 then it will display as a result. If
category=2 has children categories, any entries assigned to those children categories will also be displayed as a result, because they are within
category=2 by being a child of it.
Hope this helps! Let me know.