my solution to the touch tooltip/more info thing:
I add data-ui-action="<id>" to elements I want to attach extra info. when the info icon is selected I do querySelectorAll('[data-ui-action]') and with getBoundingClientRect I overlay a glowing box to all visible actions with a click handler that calls a callback with the action id, there I can show a popover or open the documentation for that action :)
@scott thanks! I find it useful because it allows the user to ask the UI for interactive elements (some UI designs make it hard to know what's interactive) and also to get extra information about them (even on touch devices) without requiring much change to the code (an extra action-id attribute only, event handling can be done somewhere else)
@scott also it avoids the need for a linear (and usually run once) feature tour. The user can activate it whenever she wants and jump straight to the part she wants to know more about. Also it inverts the documentation navigation, you can jump straight to the document you want from the UI.