A: yes. hit 'u' in the example viewer to show all nontree links. In densely connected datasets, the view will be much too cluttered, and you should instead turn nontree links on and off selectively. To do this, select a node (click with the left mouse so that it turns yellow) and turn on nontree links for just that node ('k' for incoming and 'w' for outgoing), or for the whole subtree beneath the node ('j' for incoming and 'v' for outgoing).
Note also that links are drawn as straight lines, so some nontree links will not be visible if they're along a straight line that's totally contained within already-drawn tree elements.
A: Try including this string in CFLAGS:
-DNAMESPACEHACK='using namespace std;'