I have a facebook page for my site that was created a while ago. And now added an APP for authentication to my site, but that also has a page and a wall can I combine them?
Application profile pages are tied to each App Id, and are separate to any existing page for your brand. There's no way to merge them, but many developers change the settings on their App's profile page to disallow posting, hide various tabs, etc. You could then add a static HTML tab to the app profile page which directs users to your existing page, and set that tab to be the default landing tab for users who arrive at the page.