Is the eshop plugin a buddypress plugin really? If it is designed to work with WordPress, it does not hook into the menu functions etc that BuddyPress uses. Contact the author of that plugin and talk to him/her about it.
What do you mean by “menus and new tabs”? If you create a plugin, you can add custom menu items related to your plugin through various hooks (see the Skeleton Component for examples), but there are no built-in drag’n’drop functions for it.
The easiest way would be to just manually edit the navigation in your bp-themes template…
If you’re using the default BP member theme, that would be located here:
Thanks Ray, your answer was right on the money.