How do I choose which way to enable/disable, start/stop, or check the status of a service?
Functionally, there is no difference between any of these invocation methods.
start and stop are symbolic links to initctl. service is a shell script that determines whether to execute the init script or use initctl.
The simplest way to see what is an Upstart job is to take a look at /etc/init/. Everything in there is an Upstart job. If you ls -l /etc/init.d/ you'll see every service and system task. The SysV init jobs will be real files, while the Upstart jobs will be symlinks to /lib/init/upstart-job which will properly invoke the Upstart job.
In other words, you can also invoke Upstart jobs by calling, for example, /etc/init.d/apport restart, though the output will suggest using service, start, or stop instead.
So, in practice it makes no difference (yet!). But if I were scripting something, I would certainly use service, start, or stop as there is almost no chance that will deprecated, whereas calling services through /etc/init.d/ could go away down the road (though probably not any time soon).
A note on disabling services: renaming the .conf file works, but I don't recommend it. You might disable a service that way, but if there is a package upgrade available, dpkg will copy down a fresh copy of the Upstart job and without intending it, your service is enabled again. The correct way to disable an Upstart job is to use a .override file which leaves the original job intact.
For example, to disable apport, simply create a file called /etc/init/apport.override that contains the word "manual".
# echo "manual" > /etc/init/apport.override
Personally, I would avoid using sysv-rc-conf. It may be safe enough to use it to modify SysV jobs, but I'm not sure; it doesn't seem to support Upstart jobs, and there's no way to tell form the interface which is which. I would stick with update-rc.d for managing SysV scripts.
For more Upstart information see:
- The Upstart Cookbook: http://upstart.ubuntu.com/cookbook/
- The command
man 5 init: http://manpages.ubuntu.com/manpages/precise/en/man5/init.5.html