(for other readers: this is relevant to Sublime Text 1 only)
The 'toggle' command toggles the value of an option. You can get the current value of an option via:
'repeat' is just shorthand for repeating the item entry in the XML that many times, each time replacing %i with an incrementing number, e.g.,
<item caption="&%I %s" command="openRecentProject 0"/>
<item caption="&%I %s" command="openRecentProject 1"/>
With regards to adding your own menu entries, the general way is to make a plugin that does want you want, and then create a menu item with the corresponding command. It's not possible to for Python commands to customize the text shown for their menu item, however.