What do the symbols in service --status-all mean? [duplicate]

To provide a shallow and unsatisfactory answer your first question:

• The command service --status-all literally runs service <name> status for each service that supports the status command. Convention is for these to return success if the service is running and an error otherwise. A [ + ] is drawn upon success and a [ - ] upon error.
• The [ ? ] is drawn for services that don't mention a status command in service <name>.

As you might have anticipated, I learned this by reading the source code.

To address the real issue—the lack of documentation—I suggest filing a polite bug report about the manpage on Launchpad. ubuntu-bug sysvinit-utils should get you started.

services-admin was removed from the default installation some releases ago due to the fact that it was unable to handle Upstart jobs.

In 10.10, a utility to manage services has returned: jobs-admin will be able to control and configure both Upstart and System V jobs/services. If you'd like to give this a try now, check out the jobs-admin/jobservice PPA.

As for the symbols in your question, I believe + is running/enabled, ? is configured to start but may not be currently running (run-once, maybe), and - is likely disabled or not running.

Disclaimer: I am the developer of jobs-admin and jobservice and worked on it as a summer of code project for Ubuntu. It is not available on a default installation, but I'd like to work towards that for 11.04.