File_column - filtering uploaded file type and storing image

Sorry, more newby FC questions!

I would like to use one file upload field to upload both PDFs and
The images are in the listing_images table and PDFs are in the
listing_pdfs table - both have a one-to-many relationship with listings.
How do I do this?

For listing_images, I would like to store the width and height of the
image so I can produce valid xhtml image tags. I can’t see anything in
the file_column docs (I am using latest version from SVN trunk) to
this is possible without hacking the file_column source. Has anyone
this, and how?

Many thanks,