First off what SP level do you have in your NW73 system?
I'm not 100% sure but I don't think the two parameters are dependent from each other.
Can you share the business requirement for URL session tracking? Setting url-session-tracking to true means that URL rewriting is always done where as with the default setting (false) cookies will be used if the client supports it, otherwise URL rewriting will be used.
Setting SessionIdRegenerationEnabled to true will enable additional checks, another parameter (JSessionMarkId) is automatically generated.