How do I enable the Visual Composer page builder for Portfolio/Project items?
By default, the Visual Composer page builder is enabled for Pages only. You could enable it for other content types as well.
To enable Visual Composer on projects pages, go to Visual Composer->Role Manager and check the "portfolio" item from the list: https://www.diigo.com/item/image/4ruxh/dawn
Hit the "Save Changes" button so they could take effect.