Q: What weight of card stock to use?
A: I use 65 lb card stock, I've found the 110 lb only slightly more durable but harder to score.
Q: Which type of glue?
A: Multi-purpose white glue.
Q: Glue applicator?
A: Inexpensive (variety store) set of synthetic flat or angled paint brushes approximately 1⁄4 in or 3⁄8 in wide. The flat (sort of square) shape seems to spread the glue evenly.
Q: Printer options for PDF file?
A: To print 1/2" scale accurately select "actual size" from your printer options.
When I print a page of basic flats/doors/windows I create an inventory of flats kept in a small plastic storage tray that I can change out if I change my mind about the size of the flat.
If the pieces are small you might find it easier to gently score them before you cut them out.