I believe that couples were allowed to walk together alone as long as it didn't happen that often. Lizzy and Darcy do it before they're engaged and again after they're engaged but it's unknown to her parents.

But as for the rest of the restrictions, they did break every single one (except the intimate touching one - I don't believe there's any indication of that in the book whatsoever). And the result of all this flauting of outdated and idiotic rules (in their opinion at least) - heartbreak. Cautionary tale then?