Facebook Platform Authentication Permissions

I'm developing a web app about bookmarks. I'd like to have my own login system, but I'd like the users to be able to use FB Connect and the whole platform to invite their friends, and to post wall posts to their wall and share links.

What I should use, a log in button with the offline_ac开发者_如何学Ccess to allow the users publish wall messages, or that every time they log in to the page have to click something like "Use Facebook"?

Thank you so much!

1. No need for the offline_access permission, you need the publish_stream permission to post to the user wall. Permissions
   publish_stream
   Enables your application to post content, comments, and likes to a user's stream and to the streams of the user's friends. With this permission, you can publish content to a user's feed at any time, without requiring offline_access. However, please note that Facebook recommends a user-initiated sharing model.

2. And if the user is already has a valid session then you should display the Publish to your wall button and if not the login to facebook button