ubuntu's rc management

I hate to write these down, but I have been using these so often this winter break that I can't allow myself to do another search to find the answers.

To stop apache2 for this session only:
sudo /etc/init.d/apache2 stop

To remove apache2 permanently from startup scripts:
sudo update-rc.d apache2 remove

To reinstate apache2 in the startup scripts:
sudo update-rc.d apache2 defaults