I made a plugin to quickly add a few tabs to the navbar, and optionally you can edit a template for the dropdowns.
Basically you set a unique id for the tab, and a unique id for the sub link list. Together, xenforo knows which belongs to which and can drop down and display them accordingly when the tab is used.
The navigation template shows a few examples.
To get the Help Tab into the Forums Submenu wont be a big thing, i guess (not sure)
Two rows of Tabs.. Hmm. What if i want to make a Nav Tab a Submenus Tab that already has a Submenu?
Here is a Picture of i think it would be a good solution, but i have no idea how to code something like this.
So if you hover over Projects (in this case) SubmenuTab it should Popup a (i call it) "sided" Submenu
That would save a lot of space from the Tabs menu
And, yes i will get rid of the Help Tab since its there Twice