http://www.nsnam.org/wiki/index.php/Ns-3.7 is the wiki page for ns3.7 version which I am using.
http://www.nsnam.org/docs/manual.html is the link for the manual which is different from tutorial.

I am not giving the link for the tutorial although make sure that you follow the correct tutorial that is the one which corresponds to the version you are having.

1)

• Q. Is there a way to dereference a Ptr when in gdb?
• A. yes: p *ptr->m_ptr

2)

The boxes in the documentation have the following meaning:

• A filled gray box represents the struct or class for which the graph is generated.
• A box with a black border denotes a documented struct or class.
• A box with a grey border denotes an undocumented struct or class.
• A box with a red border denotes a documented struct or class forwhich not all inheritance/containment relations are shown. A graph is truncated if it does not fit within the specified boundaries.

The arrows have the following meaning:

• A dark blue arrow is used to visualize a public inheritance relation between two classes.
• A dark green arrow is used for protected inheritance.
• A dark red arrow is used for private inheritance.
• A purple dashed arrow is used if a class is contained or used by another class. The arrow is labeled with the variable(s) through which the pointed class or struct is accessible.
• A yellow dashed arrow denotes a relation between a template instance and the template class it was instantiated from. The arrow is labeled with the template parameters of the instance.