The functions reverse and reverse_lazy are useful for figuring out the paths from labels. If you or someone else changes the urlconf in the future, your app uses the new paths without difficulty.
If you have in your urls.py
url(r'^home/$', views.home, name='home'),
url(r'^specifics/(?P<poll_id>\d+)/$', views.detail, name='detail'),
Then in your views.py you have:
print reverse('home')
# prints /home/
print reverse('detail', args=[12])
# prints /detail/12/
As for render_to_response, it is still there and everybody still uses it.
K