Re: Q: how do I add a manu bar at the header ?
Check out the bbMenu plugin, it adds a menu to you bbPress. Don’t think it works with rtl, but perhaps you can convert the normal css (see plugin) to the rtl css
The plugin:
https://bbpress.org/forums/topic/bbmenu-12-released?replies=6
And to add a tab:
https://bbpress.org/forums/topic/plugin-addmenutab-10?replies=1
If any changes are needed in the rtl css and you make it work, let me know 
