MHO the welcome message is not sufficient for this. There should be just the most important functions there because the welcome message is usually read at most once and then the less important topics from it get forgotten.
Certainly the most important thing I am missing in Discourse is a formatting help. It should be easily accessible when the edit box is open. Something like on Stack Exchange:
The “advanced” button with a menu of the advanced formatting functions could be helpful too. Though I have the gear icon suggested by @codinghorror connected with configuration / advanced parameters and not other functions. As I noticed here in Discourse the gear icon is already being used for the user’s profile “Preferences”.
I agree that the welcome message is good for presenting the most important and some selected less important functions but IMHO it cannot supply the online help.
It is good that a user learns about the possibility to create polls but showing the syntax there is not so useful. If the user does not see use for polls while reading the welcome message or shortly later he simply forgets the syntax and probably the place where it was written too.
Man, I searched for a while before coming across your blog post via this post. I’ve taken the liberty of doing a quick and dirty copy of your post into a howto topic.
Please figure out a way to make it such that those who have the plugin installed don’t have their upgrade break because the plugin is in both the plugin list and in discourse.
If past experience (from an outside view) continues through, Discourse will likely inherit the plugin, make alterations to bring it to their standards and then the existing plugin will become an empty shell (so it shouldn’t conflict – provided you keep your version of Discourse up-to-date).