Question 1:
All side doors on 47-55 trucks had a seal (weatherstripping).
http://www.classicparts.com/1947-66--Door-Rubber-Seals-Glue-On/productinfo/03%2D011/

Jim Carter sells rear door seals (clamshell doors, if you have the original doors for your year) but they were a terrible fit when I bought them several years ago. Steele Rubber had the correct rear door seals.

Question 2: These might be a little helpful.
http://www.chevytrucks.org/tech/doorsprg.htm
http://www.classictruckshop.com/door_hinge.php