If in the admin/plugin settings, field "FAQ page url", you put the value "faq"
in the admin/pages settings, you have to click on "add link" (on the FAQ page in the "Pages available via plugins" section) and insert the string "faq" also in the field "URL of link - absolute or relative to Q2A root"
(just for testing, put "FAQ" in the "text of link" field, visible for "anybody", position "after links in footer" : you should have a "FAQ" link in the footer now)