Should I add vegetables and spices in the stock-making stage of pig-knuckle soup?
If you are going to cook a stock for 4 hours, the flavor of the vegetable will contribute to the overall flavor of the stock...but not be so great in vegetables themselves...and their texture will be very soft.  I would strain and de-fat the stock... then use the stock you created to build your soup.  Add vegetables at this point and cook just until the vegetables are cooked through.  This would provide both the best flavor and texture of the vegetables.  Use the same process if you want to puree some or all of the soup.