Should I roast meat/bones before making stock out of it?
Roasting the bones first will add a deeper flavor. The roast flavor may or may not be desired, it depends on your preferences. 

This is from the article I've posted below: "Roasting caramelizes them, heightening sweetness and deepening flavor. But any blackening will make meat stock bitter. 'You don't want that burned bone thing,' cautions Keller."

http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/10/31/FD0JSAGEJ.DTL